def p2pkh_addr
      return nil unless p2pkh?
      hash160 = chunks[2].pushed_data.bth
      return nil unless hash160.htb.bytesize == 20
      Bitcoin.encode_base58_address(hash160, Bitcoin.chain_params.address_version)
    end
def p2pkh_addr
      return nil unless p2pkh?
      hash160 = chunks[2].pushed_data.bth
      return nil unless hash160.htb.bytesize == 20
      Bitcoin.encode_base58_address(hash160, Bitcoin.chain_params.address_version)
    end
generate p2pkh address. if script dose not p2pkh, return nil.