@0x/contracts-utils: Add D18 library.
				
					
				
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		@@ -1,4 +1,13 @@
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[
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    {
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        "version": "4.4.0",
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        "changes": [
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            {
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                "note": "Add `D18` library",
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                "pr": 2466
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            }
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        ]
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    },
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    {
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        "timestamp": 1581748629,
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        "version": "4.3.1",
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										248
									
								
								contracts/utils/contracts/src/D18.sol
									
									
									
									
									
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										248
									
								
								contracts/utils/contracts/src/D18.sol
									
									
									
									
									
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							@@ -0,0 +1,248 @@
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/*
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  Copyright 2019 ZeroEx Intl.
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  Licensed under the Apache License, Version 2.0 (the "License");
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  you may not use this file except in compliance with the License.
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  You may obtain a copy of the License at
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    http://www.apache.org/licenses/LICENSE-2.0
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  Unless required by applicable law or agreed to in writing, software
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  distributed under the License is distributed on an "AS IS" BASIS,
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  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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  See the License for the specific language governing permissions and
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  limitations under the License.
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*/
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pragma solidity ^0.5.16;
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/// @dev A library for working with 18 digit, base 10 decimals.
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library D18 {
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    /// @dev Decimal places for dydx value quantities.
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    uint256 private constant PRECISION = 18;
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    /// @dev 1.0 in base-18 decimal.
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    int256 private constant DECIMAL_ONE = int256(10 ** PRECISION);
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    /// @dev Minimum signed integer value.
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    int256 private constant MIN_INT256_VALUE = int256(0x8000000000000000000000000000000000000000000000000000000000000000);
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    /// @dev Return `1.0`
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    function one()
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        internal
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        pure
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        returns (int256 r)
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    {
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        r = DECIMAL_ONE;
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    }
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    /// @dev Add two decimals.
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    function add(int256 a, int256 b)
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        internal
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        pure
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        returns (int256 r)
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    {
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        r = _add(a, b);
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    }
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    /// @dev Add two decimals.
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    function add(uint256 a, int256 b)
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        internal
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        pure
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        returns (int256 r)
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    {
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        require(int256(a) >= 0, "D18/DECIMAL_VALUE_TOO_BIG");
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        r = _add(int256(a), b);
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    }
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    /// @dev Add two decimals.
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    function add(int256 a, uint256 b)
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        internal
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        pure
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        returns (int256 r)
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    {
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        require(int256(b) >= 0, "D18/DECIMAL_VALUE_TOO_BIG");
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        r = _add(a, int256(b));
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    }
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    /// @dev Add two decimals.
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    function add(uint256 a, uint256 b)
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        internal
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        pure
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        returns (int256 r)
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    {
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        require(int256(a) >= 0, "D18/DECIMAL_VALUE_TOO_BIG");
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        require(int256(b) >= 0, "D18/DECIMAL_VALUE_TOO_BIG");
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        r = _add(int256(a), int256(b));
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    }
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    /// @dev Subract two decimals.
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    function sub(int256 a, int256 b)
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        internal
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        pure
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        returns (int256 r)
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    {
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        r = _add(a, -b);
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    }
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    /// @dev Subract two decimals.
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    function sub(uint256 a, int256 b)
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        internal
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        pure
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        returns (int256 r)
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    {
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        require(int256(a) >= 0, "D18/DECIMAL_VALUE_TOO_BIG");
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        r = _add(int256(a), -b);
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    }
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    /// @dev Subract two decimals.
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    function sub(uint256 a, uint256 b)
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        internal
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        pure
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        returns (int256 r)
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    {
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        require(int256(a) >= 0, "D18/DECIMAL_VALUE_TOO_BIG");
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        require(int256(b) >= 0, "D18/DECIMAL_VALUE_TOO_BIG");
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        r = _add(int256(a), -int256(b));
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    }
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    /// @dev Multiply two decimals.
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    function mul(int256 a, int256 b)
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        internal
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        pure
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        returns (int256 r)
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    {
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        r = _div(_mul(a, b), DECIMAL_ONE);
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    }
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    /// @dev Multiply two decimals.
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    function mul(uint256 a, int256 b)
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        internal
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        pure
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        returns (int256 r)
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    {
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        require(int256(a) >= 0, "D18/DECIMAL_VALUE_TOO_BIG");
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        r = _div(_mul(int256(a), b), DECIMAL_ONE);
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    }
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    /// @dev Multiply two decimals.
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    function mul(int256 a, uint256 b)
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        internal
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        pure
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        returns (int256 r)
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    {
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        require(int256(b) >= 0, "D18/DECIMAL_VALUE_TOO_BIG");
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        r = _div(_mul(a, int256(b)), DECIMAL_ONE);
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    }
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    /// @dev Multiply two decimals.
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    function mul(uint256 a, uint256 b)
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        internal
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        pure
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        returns (int256 r)
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    {
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        require(int256(a) >= 0, "D18/DECIMAL_VALUE_TOO_BIG");
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        require(int256(b) >= 0, "D18/DECIMAL_VALUE_TOO_BIG");
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        r = _div(_mul(int256(a), int256(b)), DECIMAL_ONE);
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    }
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    /// @dev Divide two decimals.
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    function div(int256 a, int256 b)
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        internal
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        pure
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        returns (int256 r)
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    {
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        r = _div(_mul(a, DECIMAL_ONE), b);
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    }
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    /// @dev Divide two decimals.
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    function div(uint256 a, int256 b)
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        internal
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        pure
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        returns (int256 r)
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    {
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        require(int256(a) >= 0, "D18/DECIMAL_VALUE_TOO_BIG");
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        r = _div(_mul(int256(a), DECIMAL_ONE), b);
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    }
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    /// @dev Divide two decimals.
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    function div(int256 a, uint256 b)
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        internal
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        pure
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        returns (int256 r)
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    {
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        require(int256(b) >= 0, "D18/DECIMAL_VALUE_TOO_BIG");
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        r = _div(_mul(a, DECIMAL_ONE), int256(b));
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    }
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    /// @dev Divide two decimals.
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    function div(uint256 a, uint256 b)
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        internal
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        pure
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        returns (int256 r)
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    {
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        require(int256(a) >= 0, "D18/DECIMAL_VALUE_TOO_BIG");
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        require(int256(b) >= 0, "D18/DECIMAL_VALUE_TOO_BIG");
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        r = _div(_mul(int256(a), DECIMAL_ONE), int256(b));
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    }
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    /// @dev Safely convert an unsigned integer into a signed integer.
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    function toSigned(uint256 a)
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        internal
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        pure
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        returns (int256 r)
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    {
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        require(int256(a) >= 0, "D18/DECIMAL_VALUE_TOO_BIG");
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        r = int256(a);
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    }
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    /// @dev Clip a signed value to be positive.
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    function clip(int256 a)
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        internal
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        pure
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        returns (int256 r)
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    {
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        r = a < 0 ? 0 : a;
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    }
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    /// @dev Safely multiply two signed integers.
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    function _mul(int256 a, int256 b)
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        private
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        pure
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        returns (int256 r)
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    {
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        if (a == 0 || b == 0) {
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            return 0;
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        }
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        r = a * b;
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        require(r / a == b && r / b == a, "D18/DECIMAL_MUL_OVERFLOW");
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        return r;
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    }
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    /// @dev Safely divide two signed integers.
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    function _div(int256 a, int256 b)
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        private
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        pure
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        returns (int256 r)
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    {
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        require(b != 0, "D18/DECIMAL_DIV_BY_ZERO");
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        require(a != MIN_INT256_VALUE || b != -1, "D18/DECIMAL_DIV_OVERFLOW");
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        r = a / b;
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    }
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    /// @dev Safely add two signed integers.
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    function _add(int256 a, int256 b)
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        private
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        pure
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        returns (int256 r)
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    {
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        r = a + b;
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        require(
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            !((a < 0 && b < 0 && r > a) || (a > 0 && b > 0 && r < a)),
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            "D18/DECIMAL_ADD_OVERFLOW"
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        );
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    }
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}
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