title: Transparent Legend with pandas.plot
body: <p>I checked the documentation of pandas plot</p>
  
  <p><a href="https://pandas.pydata.org/pandas-docs/version/0.18.1/generated/pandas.DataFrame.plot.html" rel="nofollow noreferrer">pd.df.plot</a></p>
  
  <p>but I could not find any option to make the legend transparent</p>
  
  <p>I know how to do it with matplotlib </p>
  
  <pre><code>subplot.legend(loc='best', fancybox=True, framealpha=0.5)
  </code></pre>
  
  <p>but I need to use pandas dataframe plot</p>
  
  <p>Any idea?</p>