title: TypeError: 'RobertaTokenizer' object is not callable
body: <p>I followed documentation on <a href="https://huggingface.co/transformers/model_doc/roberta.html" rel="nofollow noreferrer">RoBERTa</a>. and ran the following code segment:</p>
  <pre><code>from transformers import RobertaTokenizer
  tokenizer = RobertaTokenizer.from_pretrained(&quot;roberta-base&quot;)
  tokenizer(&quot;Hello world&quot;)['input_ids']
  tokenizer(&quot; Hello world&quot;)['input_ids']
  </code></pre>
  <p>Then I got the error:</p>
  <pre><code>---------------------------------------------------------------------------
  TypeError                                 Traceback (most recent call last)
  &lt;ipython-input-12-b70f7dbb4c6e&gt; in &lt;module&gt;
        1 from transformers import RobertaTokenizer
        2 tokenizer = RobertaTokenizer.from_pretrained(&quot;roberta-base&quot;)
  ----&gt; 3 tokenizer(&quot;Hello world&quot;)['input_ids']
        4 tokenizer(&quot; Hello world&quot;)['input_ids']
  
  TypeError: 'RobertaTokenizer' object is not callable
  </code></pre>
  <p>I found a <a href="https://github.com/huggingface/transformers/issues/5580" rel="nofollow noreferrer">fix suggestion</a> that says that we need to install transformers version &gt; 3.0.0. Then the installation log looks like:</p>
  <pre><code>allennlp 1.0.0 requires transformers&lt;2.12,&gt;=2.9, but you'll have transformers 3.1.0 which is incompatible.
  Successfully installed tokenizers-0.8.1rc2 transformers-3.1.0
  </code></pre>
  <p>But the we still getting the same error of 'RobertaTokenizer' object is not callable.</p>