Function input_one_arg:
Defined in module m_input (file: /secure/modules/m_input.c)

Get a single argument and call a given function pointer with it.  If the
argument isn't present (arg == 0), then the prompt is used to ask for
the value.

Prototype:
protected varargs nomask void input_one_arg(
    string arg_prompt,
    function fp,
    string arg
    );
