def __sub__(self, other):
        if isinstance( other, basestring ):
            other = ParserElement.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 And( [ self, And._ErrorStop(), other ] )
Implementation of - operator, returns C{L{And}} with error stop
dataset/ETHPy150Open pypa/pip/pip/_vendor/pyparsing.py/ParserElement.__sub__