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

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()