code: def from_bytes(b):
          
          if len(b) != 64:
              raise ValueError("from_bytes: Signature length != 64.")
          r = int.from_bytes(b[0:32], 'big')
          s = int.from_bytes(b[32:64], 'big')
          return Signature(r, s)
docs: Extracts the r and s components from a byte string.
  
          Args:
              b (bytes): A 64-byte long string. The first 32 bytes are
                 extracted as the r component and the second 32 bytes
                 are extracted as the s component.
  
          Returns:
              Signature: A Signature object.
  
          Raises:
              ValueError: If signature is incorrect length