// SPDX-License-Identifier: GPL-3.0
pragma solidity >=0.7.5;

interface IERC1271 {
    // bytes4(keccak256("isValidSignature(bytes32,bytes)")
    //   bytes4 constant internal MAGICVALUE = 0x1626ba7e;

  /**
   * @dev Should return whether the signature provided is valid for the provided hash
   * @param _hash      Hash of the data to be signed
   * @param _signature Signature byte array associated with _hash
   *
   * MUST return the bytes4 magic value 0x1626ba7e when function passes.
   * MUST NOT modify state (using STATICCALL for solc < 0.5, view modifier for solc > 0.5)
   * MUST allow external calls
   */ 
  function isValidSignature(
    bytes32 _hash, 
    bytes memory _signature)
    external
    view 
    returns (bytes4 magicValue);
}