pragma solidity 0.5.10;


contract Echo {
  address masterCopy;

  function helloWorld() external pure returns (string memory)  {
    return "hello world";
  }

  function helloWorldArg(string calldata arg)
    external
    pure
    returns (string memory)
  {
    return arg;
  }

  function msgSender() external view returns (address) {
    return msg.sender;
  }

  function returnArg(bool arg) external pure returns (bool) {
    return arg;
  }
}