what is _show in python / TkMessageBox?

[Varunkrishna]

I was learning python(v2.7) and Tkinter. Suddenly I came across the module TkMessageBox in that I came across a strange thing _show

def askyesnocancel(title=None, message=None, **options):
    "Ask a question; return true if the answer is yes, None if cancelled."
    s = _show(title, message, QUESTION, YESNOCANCEL, **options)
    # s might be a Tcl index object, so convert it to a string
    s = str(s)
    if s == CANCEL:
        return None
    return s == YES

Why _show is used? What is so special about that _show()? Why it is preceded with an Underscore(_) Chararcter?

[bvdet]

The leading underscore character is an indicator that the variable is for "weak internal use". Normally you would not call _show() except for module internal use.

BTW - the module is tkMessageBox (note lower case "t")