title: ImportError: cannot import name 'cross_validate'
body: <p>I'm trying to do:</p>
  
  <pre><code>from sklearn.model_selection import cross_validate
  </code></pre>
  
  <p>as mentioned <a href="http://scikit-learn.org/stable/modules/cross_validation.html#the-cross-validate-function-and-multiple-metric-evaluation" rel="noreferrer">here</a>.
  But get the error:</p>
  
  <pre><code>ImportError: cannot import name 'cross_validate'
  </code></pre>
  
  <p>Everything else in Sklearn seems to work fine, it's just this bit. Error even occurs when I run this one line and nothing else.</p>