code: def eth_sign_sha3(data: bytes) -> bytes:
      
      prefix = b'\x19Ethereum Signed Message:\n'
      if not data.startswith(prefix):
          data = prefix + b'%d%s' % (len(data), data)
      return keccak(data)
docs: eth_sign/recover compatible hasher
      Prefixes data with "\x19Ethereum Signed Message:\n<len(data)>"