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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def command_prompt(pymux, variables):
 """ Enter command prompt. """

    client_state = pymux.get_client_state()

    if variables['<command>']:
        # When a 'command' has been given.
        client_state.prompt_text = variables['<message>'] or '(%s)' % variables['<command>'].split()[0]
        client_state.prompt_command = variables['<command>']

        client_state.prompt_mode = True
        client_state.prompt_buffer.reset(Document(
            format_pymux_string(pymux, variables['<default>'] or '')))

        get_app().layout.focus(client_state.prompt_buffer)
    else:
        # Show the ':' prompt.
        client_state.prompt_text = ''
        client_state.prompt_command = ''

        get_app().layout.focus(client_state.command_buffer)

    # Go to insert mode.
    get_app().vi_state.input_mode = InputMode.INSERT