ccokee

// SPDX-License-Identifier: MIT
pragma solidity ^0.6.0;

abstract contract LinkTokenReceiver {

  bytes4 constant private ORACLE_REQUEST_SELECTOR = 0x40429946;
  uint256 constant private SELECTOR_LENGTH = 4;
  uint256 constant private EXPECTED_REQUEST_WORDS = 2;
  uint256 constant private MINIMUM_REQUEST_LENGTH = SELECTOR_LENGTH + (32 * EXPECTED_REQUEST_WORDS);
  /**

ccokee

pragma solidity ^0.4.23;

contract CrudApp {
    
   struct country{
      string name;
      string leader;
      uint256 population;
   }