def __sub__(self, other):
        """
        Implementation of - operator, returns :class:`And` with error stop
        """
        if isinstance(other, basestring):
            other = self._literalStringClass(other)
        if not isinstance(other, ParserElement):
            warnings.warn("Cannot combine element of type %s with ParserElement" % type(other),
                          SyntaxWarning, stacklevel=2)
            return None
        return self + And._ErrorStop() + other

        Implementation of - operator, returns :class:`And` with error stop
        
product/gradle-plugin/src/main/python/pip/_vendor/pyparsing.py