Return a string containing dashes (optional) and GO ID.

def _str_dash(self, depth, no_repeat, obj):
        """Return a string containing dashes (optional) and GO ID."""
        if self.indent:
            # '-' is default character indicating hierarchy level
            # '=' is used to indicate a hierarchical path printed in detail previously.
            single_or_double = not no_repeat or not obj.children
            letter = '-' if single_or_double else '='
            return ''.join([letter]*depth)
        return ""