docs: def _stmt_graph_add_edge(self, src, dst, **edge_labels):
          """
          Add an edge in the statement dependence graph from a program location `src` to another program location `dst`.
  
          :param CodeLocation src: Source node.
          :param CodeLocation dst: Destination node.
          :param edge_labels: All labels associated with the edge.
          :returns: None
          """
  
          # Is that edge already in the graph ?
          # If at least one is new, then we are not redoing the same path again
          if src in self._stmt_graph and dst in self._stmt_graph[src]:
              return
  
          self._stmt_graph.add_edge(src, dst, **edge_labels)