docs: def validate_and_decode(jwt_bu64, cert_obj):
      """Example for validating the signature of a JWT using only the cryptography
      library.
  
      Note that this does NOT validate the claims in the claim set.
  
      """
      public_key = cert_obj.public_key()
      message = '.'.join(d1_common.cert.jwt.get_bu64_tup(jwt_bu64)[:2])
      signature = d1_common.cert.jwt.get_jwt_tup(jwt_bu64)[2]
      try:
          public_key.verify(
              signature,
              message,
              cryptography.hazmat.primitives.asymmetric.padding.PKCS1v15(),
              cryptography.hazmat.primitives.hashes.SHA256(),
          )
      except cryptography.exceptions.InvalidSignature as e:
          raise Exception('Signature is invalid. error="{}"'.format(str(e)))
      return d1_common.cert.jwt.get_jwt_dict(jwt_bu64)