Return a pretty formatted representation of self.

def pretty(self, indent=0, debug=False):
        """
        Return a pretty formatted representation of self.
        """
        debug_details = ''
        if debug:
            debug_details += '<isliteral=%r, iscanonical=%r>' % (self.isliteral, self.iscanonical)

        obj = "'%s'" % self.obj if isinstance(self.obj, basestring) else repr(self.obj)
        return (' ' * indent) + ('%s(%s%s)' % (self.__class__.__name__, debug_details, obj))