pragma solidity ^0.6.0; import "../utils/EnumerableSet.sol"; contract EnumerableSetMock { using EnumerableSet for EnumerableSet.AddressSet; event OperationResult(bool result); EnumerableSet.AddressSet private _set; function contains(address value) public view returns (bool) { return _set.contains(value); } function add(address value) public { bool result = _set.add(value); emit OperationResult(result); } function remove(address value) public { bool result = _set.remove(value); emit OperationResult(result); } function length() public view returns (uint256) { return _set.length(); } function at(uint256 index) public view returns (address) { return _set.at(index); } }