code: def remove_na(self, data, remove_na_how):
          
          data = data.dropna(how=remove_na_how)        
          return data
docs: Remove NAs from dataframe.
  
          Parameters
          ----------
          data            : pd.DataFrame()
              Dataframe to remove NAs from.
          remove_na_how   : str
              Specificies how to remove NA i.e. all, any...
  
          Returns
          -------
          pd.DataFrame()
              Dataframe with NAs removed.