def _start_timer(self, key: str) -> None:
    if (key in self._timers):
        return
    if (key == 'update_candidates'):
        self._timers[key] = self._vim.call('denite#helper#_start_update_candidates_timer', self._bufnr)
    elif (key == 'update_buffer'):
        self._timers[key] = self._vim.call('denite#helper#_start_update_buffer_timer', self._bufnr)
def _start_timer(self, key: str) -> None:
    if (key in self._timers):
        return
    if (key == 'update_candidates'):
        self._timers[key] = self._vim.call('denite#helper#_start_update_candidates_timer', self._bufnr)
    elif (key == 'update_buffer'):
        self._timers[key] = self._vim.call('denite#helper#_start_update_buffer_timer', self._bufnr)