Function plan_connect_by_inserting_node 

pub fn plan_connect_by_inserting_node(
    graph: &Graph,
    a: PortId,
    b: PortId,
    first_edge_id: EdgeId,
    second_edge_id: EdgeId,
    inserted: InsertNodeSpec,
) -> ConnectPlan

Plans connecting two ports by inserting a node with default interaction policy.