A Graph is a finite number of vertices.
TODO : some more informations could be calculated :

• isBipartite
• isConnected (isolated/connexe node groups)
• cut-vertex (nodes when remove which raise number of connexe node groups)
• cut-edge (edges when remove which raise number of connexe node groups)
• Kuratowski theorem to find if graph is planar
• chromatic number

Get all vertices attached to this graph.
return  Sequence all vertices, never null

Get all edges attached to this graph.
return  Sequence all edges, never null

Create a new vertex, but does not add it in the graph.
return  Vertex created vertex

Create a new edge, but does not add it in the graph.
param  v1 first edge vertex
param  v2 second edge vertex
return  Edge created edge

Add given vertex in the graph.
param  vertex vertex to add in the graph

Add given edge in the graph.
param  edge edge to add in the graph

Remove given vertex from the graph.
param  vertex vertex to remove from the graph

Remove given edge from the graph.
param  edge edge to remove from the graph

A Graph is simple when it does not contain parallale or loop edges.
return  true if graph is simple

A Graph is a multi graph if it contains parallale edges.
return  true if graph is simple

A Graph is a pseudo graph if it contains parallale or loop edges.
return  true if graph is a pseudograph

A Graph is complete if all vertices are linked to all others vertices.
return  true if graph is complete