code: def bad_signatures(self):  # pragma: no cover
          
          for s in [ i for i in self._subjects if not i.verified ]:
              yield s
docs: A generator yielding namedtuples of all signatures that were not verified
          in the operation that returned this instance. The namedtuple has the following attributes:
  
          ``sigsubj.verified`` - ``bool`` of whether the signature verified successfully or not.
  
          ``sigsubj.by`` - the :py:obj:`~pgpy.PGPKey` that was used in this verify operation.
  
          ``sigsubj.signature`` - the :py:obj:`~pgpy.PGPSignature` that was verified.
  
          ``sigsubj.subject`` - the subject that was verified using the signature.