title: Python Pandas Dataframe, remove all rows where 'None' is the value in any column
body: <p>I have a large dataframe. When it was created 'None' was used as the value where a number could not be calculated (instead of 'nan')</p>
  
  <p>How can I delete all rows that have 'None' in any of it's columns? I though I could use <code>df.dropna</code> and set the value of <code>na</code>, but I can't seem to be able to.</p>
  
  <p>Thanks</p>
  
  <p>I think this is a good representation of the dataframe:</p>
  
  <pre><code>temp = pd.DataFrame(data=[['str1','str2',2,3,5,6,76,8],['str3','str4',2,3,'None',6,76,8]])
  </code></pre>