title: Combine rows with same value, and merge together
body: <p>I've got a dataframe from pandas, where i check how often a word appears in a text.</p>
  <p>Now the word Year for example appears 40.000 times in a text, a little bit further below the same word Year also appears 12.000</p>
  <p>I want to create a new dataframe, that removes the duplicates but adds the total count of year.</p>
  <p><img src="https://i.stack.imgur.com/dte1G.png" alt="Image of DF" /></p>