title: How to get the first group in a groupby of multiple columns?
body: <p>I've been trying to figure out how I can return just the first group, after I apply groupby. </p>
  
  <p>My code looks like this: </p>
  
  <pre><code>gb = df.groupby(['col1', 'col2', 'col3', 'col4'])['col5'].sum()
  </code></pre>
  
  <p>What I want is for that first first group to output. I've been trying the get_group method but it keeps failing (maybe because I am grouping by multiple columns?)</p>
  
  <p>Here is an example of my output:</p>
  
  <pre><code>col1  col2  col3   col4  'sum'
   1     34   green   10    0.0
              yellow  30    1.5 
              orange  20    1.1 
   2     89   green   10    3.0 
              yellow   5    0.0 
              orange  10    1.0
  </code></pre>
  
  <p>What I want to be returned is just this: </p>
  
  <pre><code>col1  col2  col3   col4  'sum'
   1     34   green   10    0.0
              yellow  30    1.5 
              orange  20    1.1 
  </code></pre>
  
  <p>(Note the 'sum' column I just added here to make it clear what that last column was, but pandas does not actually name that column)</p>