docs: def del_edge(self, u_vertex, v_vertex):
          """Removes the edge ``u_vertex -> v_vertex`` from the graph if the edge is present.
  
          :param u_vertex: Vertex
          :param v_vertex: Vertex
          :return: ``True`` if the existing edge was removed. ``False`` otherwise.
          """
          if self.is_edge(u_vertex, v_vertex):
              self.indegrees[v_vertex] -= 1
              self.adj_dict[u_vertex].remove(v_vertex)
              return True
  
          return False