code: def fun_en_complete_func(self, client, findstart_and_base, base=None):
          
          if isinstance(findstart_and_base, list):
              # Invoked by neovim
              findstart = findstart_and_base[0]
              base = findstart_and_base[1]
          else:
              # Invoked by vim
              findstart = findstart_and_base
          return client.complete_func(findstart, base)
docs: Invokable function from vim and neovim to perform completion.