code: def write(self, bucket, rows):
          
  
          # Prepare
          descriptor = self.describe(bucket)
          new_data_frame = self.__mapper.convert_descriptor_and_rows(descriptor, rows)
  
          # Just set new DataFrame if current is empty
          if self.__dataframes[bucket].size == 0:
              self.__dataframes[bucket] = new_data_frame
  
          # Append new data frame to the old one setting new data frame
          # containing data from both old and new data frames
          else:
              self.__dataframes[bucket] = pd.concat([
                  self.__dataframes[bucket],
                  new_data_frame,
              ])
docs: https://github.com/frictionlessdata/tableschema-pandas-py#storage