docs: def dependency_graph(self, filename=None):
          """Visualize the computational graph.
  
          :param filename: Filename of the output image together with file extension. Supported formats: `png`, `jpg`,
              `pdf`, ... . Check `graphviz` Python package for more options
          :type filename: str
          :return: The DOT representation of the computational graph, with some more formatting
          :rtype: Digraph
          """
          dot = self.get_dot()
          dot.attr(rankdir='LR')  # Show graph from left to right
  
          if filename is not None:
              file_name, file_format = filename.rsplit('.', 1)
  
              dot.render(filename=file_name, format=file_format, cleanup=True)
  
          return dot