def __add__(self, other ):
        """
        Implementation of + operator - returns C{L{And}}. Adding strings to a ParserElement
        converts them to L{Literal}s by default.
        
        Example::
            greet = Word(alphas) + "," + Word(alphas) + "!"
            hello = "Hello, World!"
            print (hello, "->", greet.parseString(hello))
        Prints::
            Hello, World! -> ['Hello', ',', 'World', '!']
        """
        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, other ] )

        Implementation of + operator - returns C{L{And}}. Adding strings to a ParserElement
        converts them to L{Literal}s by default.
        
        Example::
            greet = Word(alphas) + "," + Word(alphas) + "!"
            hello = "Hello, World!"
            print (hello, "->", greet.parseString(hello))
        Prints::
            Hello, World! -> ['Hello', ',', 'World', '!']
        
src/pkg_resources/_vendor/pyparsing.py