docs: def remove_vertex(self, vertex):
          """
          Remove vertex from G
          """
          try:
              self.vertices.pop(vertex)
          except KeyError:
              raise GraphInsertError("Vertex %s doesn't exist." % (vertex,))
          if vertex in self.nodes:
              self.nodes.pop(vertex)
          for element in self.vertices:
              if vertex in self.vertices[element]:
                  self.vertices[element].remove(vertex)
          edges = []  # List for edges that include vertex
          for element in self.edges:
              if vertex in element:
                  edges.append(element)
          for element in edges:
              del self.edges[element]