title: tensorflow in R on Windows tf$ error
body: <p>I loaded package <code>tensorflow</code> and run <code>library(tensorflow)</code>. I got the message that tf is masked by <code>.GlobalEnv</code>. Not sure what that means, but it seemed not to be an error.</p>
  
  <p>I then ran <code>install_tensorflow()</code> and that seems to run fine. I now ran <code>library(tensorflow)</code> again without a message.</p>
  
  <p>When checking the tensorflow installation with <code>tf_config()</code> I get the tensorflow information (version v.1.4.0) and Python v3.6.</p>
  
  <p>It all seemed OK. But when I am running <code>hello &lt;- tf$constant('Hello, TensorFlow!')</code> or any other <code>tf$XXX</code>, I get the error:</p>
  
  <blockquote>
    <p>Error in tf$constant : $ operator is invalid for atomic vectors.</p>
  </blockquote>
  
  <p>So somehow tensorflow is not correctly installed. <code>?tf</code> opens the right description for the tensorflow module.</p>
  
  <p>Anyone has an idea?</p>