docstr: A proxy-call to the dataframe's `.groupby()`.
code: def groupby(self, by):
      """
      A proxy-call to the dataframe's `.groupby()`.
      """
      return self.dataframe.groupby(by=by)
  
imports: from abc import ABC
label_desc: Use image node_id 20 for calling the DataframeAbstract obj's underlying member method code with example usage: obj.groupby(by) and returns: self