title: Specify type for arbitrary data types
body: <p>I have the following code in Python <code>3.6.6</code>:</p>
  
  <pre><code>import pandas as pd
  df_test = pd.read_csv('./test.csv')
  df_test_cor_cols: pandas.core.frame.DataFrame = df_test[selected_cols]
  </code></pre>
  
  <p>The problem is that on the last line I get:</p>
  
  <blockquote>
    <p>NameError: name 'pandas' is not defined</p>
  </blockquote>
  
  <p>So, is there a way in Python <code>3.6.6</code>(or any other version) to specify the type for arbitrary data types such <code>panda</code>?</p>