comint-line-beginning-position
comint-line-beginning-position is a compiled Lisp function in `comint.el
'.
(comint-line-beginning-position)
Return the buffer position of the beginning of the line, after any prompt.
If `comint-use-prompt-regexp' is non-nil, then the prompt skip is done by
skipping text matching the regular expression `comint-prompt-regexp',
a buffer local variable.