parameters: (self, signature_filename, data_filename,
                           keystore=None)
return_statement: return rc == 0
docstring: Verify a signature for a file.
  
          :param signature_filename: The pathname to the file containing the
                                     signature.
          :param data_filename: The pathname to the file containing the
                                signed data.
          :param keystore: The path to a directory which contains the keys
                           used in verification. If not specified, the
                           instance's ``gpg_home`` attribute is used instead.
          :return: True if the signature was verified, else False.
docstring_summary: Verify a signature for a file.
docstring_tokens: Verify a signature for a file .
function: def verify_signature(self, signature_filename, data_filename,
                           keystore=None):
          """
          Verify a signature for a file.
  
          :param signature_filename: The pathname to the file containing the
                                     signature.
          :param data_filename: The pathname to the file containing the
                                signed data.
          :param keystore: The path to a directory which contains the keys
                           used in verification. If not specified, the
                           instance's ``gpg_home`` attribute is used instead.
          :return: True if the signature was verified, else False.
          """
          if not self.gpg:
              raise DistlibException('verification unavailable because gpg '
                                     'unavailable')
          cmd = self.get_verify_command(signature_filename, data_filename,
                                        keystore)
          rc, stdout, stderr = self.run_command(cmd)
          if rc not in (0, 1):
              raise DistlibException('verify command failed with error '
                               'code %s' % rc)
          return rc == 0
function_tokens: def verify_signature ( self , signature_filename , data_filename , keystore = None ) : if not self . gpg : raise DistlibException ( 'verification unavailable because gpg ' 'unavailable' ) cmd = self . get_verify_command ( signature_filename , data_filename , keystore ) rc , stdout , stderr = self . run_command ( cmd ) if rc not in ( 0 , 1 ) : raise DistlibException ( 'verify command failed with error ' 'code %s' % rc ) return rc == 0