@classmethod
    def filtered_on(cls, query, tag):
        # ! this assumes the ast is in the simple format without nests etc.
        for cond in query['ast']:
            if cond[0].startswith('match_tag') and cond[1] == tag:
                return cond
        return False
does the given query filter on given tag? if so return first filter
dataset/ETHPy150Open vimeo/graph-explorer/graph_explorer/query.py/Query.filtered_on