title: Summing multiple rows having duplicate columns pandas
body: <p>Consider this dataframe</p>
  
  <p><code>df = pd.DataFrame({'a': [1,2,1,3,4,2], 'c':['dd','ee','dd','as','ae','ee'], 'count':[5,9,1,6,8,3]})</code></p>
  
  <pre><code>   a   c  count
  0  1  dd      5
  1  2  ee      9
  2  1  dd      1
  3  3  as      6
  4  4  ae      8
  5  2  ee      3
  </code></pre>
  
  <p>As you can see there  are duplicates in column 'a' <code>1 and 2</code> are repeated multiple times.</p>
  
  <p>i want to sum the count of such in pandas  like in sql we do groupby.</p>
  
  <p>my final df should look like this</p>
  
  <pre><code>   a   c  count
  0  1  dd      6
  1  2  ee      12
  2  3  as      6
  3  4  ae      8
  </code></pre>
  
  <p>i tried by using 
  <code>df = df.groupby('a')</code> but it is returning me</p>
  
  <pre><code>&lt;pandas.core.groupby.DataFrameGroupBy object
  </code></pre>