def plot(message, duration=1, ax=None):
    """
    Plot a message

    Returns: ax a Matplotlib Axe
    """
    lst_bin = _encode_binary(message)
    x, y = _create_x_y(lst_bin, duration)
    ax = _create_ax(ax)
    ax.plot(x, y, linewidth=2.0)
    delta_y = 0.1
    ax.set_ylim(-delta_y, 1 + delta_y)
    ax.set_yticks([0, 1])
    delta_x = 0.5 * duration
    ax.set_xlim(-delta_x, len(lst_bin) * duration + delta_x)
    return ax
Plot a message

    Returns: ax a Matplotlib Axe