code: def _init_incremental_search(self, searchfun, init_event):
          u
          log("init_incremental_search")
          self.subsearch_query = u''
          self.subsearch_fun = searchfun
          self.subsearch_old_line = self.l_buffer.get_line_text()
  
          queue = self.process_keyevent_queue
          queue.append(self._process_incremental_search_keyevent)
  
          self.subsearch_oldprompt = self.prompt
  
          if (self.previous_func != self.reverse_search_history and
              self.previous_func != self.forward_search_history):
              self.subsearch_query = self.l_buffer[0:Point].get_line_text()
  
          if self.subsearch_fun == self.reverse_search_history:
              self.subsearch_prompt = u"reverse-i-search%d`%s': "
          else:
              self.subsearch_prompt = u"forward-i-search%d`%s': "
  
          self.prompt = self.subsearch_prompt%(self._history.history_cursor, "")
  
          if self.subsearch_query:
              self.line = self._process_incremental_search_keyevent(init_event)
          else:
              self.line = u""
docs: u"""Initialize search prompt