library Address {
  /**
   * @dev Returns true if `account` is a contract.
   *
   * [IMPORTANT]
   * ====
   * It is unsafe to assume that an address for which this function returns
   * false is an externally-owned account (EOA) and not a contract.
   *
   * Among others, `isContract` will return false for the following
   * types of addresses:
   *
   *  - an externally-owned account
   *  - a contract in construction
   *  - an address where a contract will be created
   *  - an address where a contract lived, but was destroyed
   * ====
   */
  function isContract(address account) internal view returns (bool) {
    // This method relies on extcodesize, which returns 0 for contracts in
    // construction, since the code is only stored at the end of the
    // constructor execution.

    uint256 size;
    assembly {
      size := extcodesize(account)
    }
    return size > 0;
  }
}
/**
 * @dev Collection of functions related to the address type
 */
function isContract(address account) internal view returns (bool) {
  // This method relies on extcodesize, which returns 0 for contracts in
  // construction, since the code is only stored at the end of the
  // constructor execution.

  uint256 size;
  assembly {
    size := extcodesize(account)
  }
  return size > 0;
}

/**
 * @dev Returns true if `account` is a contract.
 *
 * [IMPORTANT]
 * ====
 * It is unsafe to assume that an address for which this function returns
 * false is an externally-owned account (EOA) and not a contract.
 *
 * Among others, `isContract` will return false for the following
 * types of addresses:
 *
 *  - an externally-owned account
 *  - a contract in construction
 *  - an address where a contract will be created
 *  - an address where a contract lived, but was destroyed
 * ====
 */