<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def save_image(self, image_file):
 """ Saves the image file to disk. """

        self.ensure_pyplot()
        command = 'plt.gcf().savefig("%s")'%image_file
        #print 'SAVEFIG', command  # dbg
        self.process_input_line('bookmark ipy_thisdir', store_history=False)
        self.process_input_line('cd -b ipy_savedir', store_history=False)
        self.process_input_line(command, store_history=False)
        self.process_input_line('cd -b ipy_thisdir', store_history=False)
        self.process_input_line('bookmark -d ipy_thisdir', store_history=False)
        self.clear_cout()