title: How to plot two different dataframe columns at time based on the same datetime x-axis
body: <p>Hi I have a dataframe like this:</p>
  
  <pre><code>        Date  Influenza[it]  Febbre[it]  Cefalea[it]  Paracetamolo[it]  \
  0    2008-01            989        2395         1291              2933   
  1    2008-02            962        2553         1360              2547   
  2    2008-03           1029        2309         1401              2735   
  3    2008-04           1031        2399         1137              2296    
  
       Unnamed: 6 tot_incidence  
  0           NaN          4.56  
  1           NaN          5.98  
  2           NaN          6.54  
  3           NaN          6.95  
  </code></pre>
  
  <p>I'd like to plot different figures with on x-axis the <code>Date</code> column and the y-axis the <code>Influenza[it]</code> column and another column like <code>Febbre[it]</code>. Then again x-axis the <code>Date</code> column, y-axis <code>Influenza[it]</code> column and another column (ex. <code>Paracetamolo[it]</code>) and so on. I'm trying to figure out if there is a fast way to make it without completely manipulate the dataframes.</p>