Syntactic sugar around to make it easier to get fine-grained access
        to the parts of a file without composing a PhyloSchema object.
        Possible invocations include:
            w.get('pg_10')
            w.get('pg_10', 'trees')
            w.get('pg_10', 'trees', format='nexus')
            w.get('pg_10', tree_id='tree3')
        see:

def get(self, collection_id, content=None, **kwargs):
        """Syntactic sugar around to make it easier to get fine-grained access
        to the parts of a file without composing a PhyloSchema object.
        Possible invocations include:
            w.get('pg_10')
            w.get('pg_10', 'trees')
            w.get('pg_10', 'trees', format='nexus')
            w.get('pg_10', tree_id='tree3')
        see:
        """
        assert COLLECTION_ID_PATTERN.match(collection_id)
        r = self.get_collection(collection_id)
        if isinstance(r, dict) and ('data' in r):
            return r['data']
        return r