docs: def render(self, fname=''):
          """Render the circuit expression and store the result in a file
  
          Args:
              fname (str): Path to an image file to store the result in.
  
          Returns:
              str: The path to the image file
          """
          import qnet.visualization.circuit_pyx as circuit_visualization
          from tempfile import gettempdir
          from time import time, sleep
  
          if not fname:
  
              tmp_dir = gettempdir()
              fname = os.path.join(tmp_dir, "tmp_{}.png".format(hash(time)))
  
          if circuit_visualization.draw_circuit(self, fname):
              done = False
              for k in range(20):
                  if os.path.exists(fname):
  
                      done = True
                      break
                  else:
                      sleep(.5)
              if done:
                  return fname
  
          raise CannotVisualize()