// SPDX-License-Identifier: GPL-3.0 pragma solidity >=0.6.0 <0.7.0; library UInt256Array { function remove(uint256[] storage self, uint256 index) internal { require(index < self.length, "UInt256Array/unknown-index"); self[index] = self[self.length-1]; delete self[self.length-1]; self.pop(); } }