def verifyZshNames(self):
        """
        Ensure that none of the option names given in the metadata are typoed
        @return: L{None}
        @raise ValueError: Raised if unknown option names have been found.
        """
        def err(name):
            raise ValueError("Unknown option name \"%s\" found while\n"
                "examining Completions instances on %s" % (
                    name, self.options))

        for name in itertools.chain(self.descriptions, self.optActions,
                                    self.multiUse):
            if name not in self.allOptionsNameToDefinition:
                err(name)

        for seq in self.mutuallyExclusive:
            for name in seq:
                if name not in self.allOptionsNameToDefinition:
                    err(name)

        Ensure that none of the option names given in the metadata are typoed
        @return: L{None}
        @raise ValueError: Raised if unknown option names have been found.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/python/_shellcomp.py