Function process_operator 

pub fn process_operator(
    operator: &Operator,
    feed_hashmap: &mut HashMap<FeedId, Feed>,
    operator_hashmap: &mut HashMap<OperatorId, Operator>,
    operator_to_feed_hashmap: &mut HashMap<OperatorId, Vec<FeedPairInfo>>,
    feed_to_operator_pairs_hashmap: &mut HashMap<FeedId, Vec<OperatorPairInfo>>,
    parent_feed_id: Option<&str>,
)