Construct conceptual models for the following types of graphs, using ER (Entity-Relationship) Diagrams:

1. directed graphs Directed graphs consist of nodes and directed edges be- tween nodes.

2. hypergraphs Hypergraphs consist of nodes and hyperedges between these nodes. A hyperedge has multiple (at least one) sources and a single target.

3. multigraphs Multigraphs consist of nodes and undirected edges between these nodes. As opposed to undirected graphs, there may be multiple edges between the same pair of nodes.

For each of your conceptual models create a sample graph and show this graph as a population of your model.