'Process rdf data through the filter.
Filters sift data according to filter rules. Data that passes the filter
rule is kept, other data is dropped.
If no filter method is provided, the data is returned as a list.
Otherwise, a items that meet filter conditions are returned in a list.
Args:
rdf_data: Host data that has already been processed by a Parser into RDF.
Returns:
A list containing data items that matched the filter rules.'

def Parse(self, rdf_data):

    if self._filter:
        return list(self._filter.Parse(rdf_data, self.expression))
    return rdf_data
