Set and control the prompt
set_prompt(value)suspend()
restore()
toggle()
No return value, called for side effects.
A character string for a static prompt, or a function that is called after the evaluation every expression typed at the R prompt. The function should always return a character scalar.
Function update_prompt() is used to replace the default R
prompt with a custom prompt. A custom prompt can be disabled
with suspend() and then re-enable with restore().
Function toggle() toggles between the two.