'Process the user input.'

def _proc(self, text):

    result = self.procfunc(text)
    if ((result is not None) and isinstance(result, basestring)):
        iterl = self.textbuffer.get_end_iter()
        self.textbuffer.insert(iterl, (result + '\n'))
        self.scroll_to_mark(self.textbuffer.get_insert(), 0)
    self._prompt()
