Mutation concepts

The mutation concepts define the different ways a graph can be modified. The hierarchy of mutation interface duplicates the traversal hierarchy and adds functionality to mutate the graph.

• IMutableGraph defines a graph that can be cleared.
• IMutableIncidenceGraph defines methods to remove out-edges.
• IMutableVertexListGraph defines methods to add and remove vertices.
• IMutableEdgeListGraph defines methods to add and remove edges.
• IMutableVertexAndEdgeListGraph merges the two above concepts.
• IMutableBidirectionalGraph defines method to remove out-edges.