code: def short_text__str(self, column_name, output_column_prefix):
          
  
          from ._ngram_counter import NGramCounter
          from ._tfidf import TFIDF
  
          return [NGramCounter(features=[column_name],
                               n = 3,
                               method = "character",
                               output_column_prefix = output_column_prefix),
  
                   TFIDF(features=[column_name],
                         min_document_frequency=0.01,
                         max_document_frequency=0.5,
                         output_column_prefix = output_column_prefix)]
docs: Transforms short text into a dictionary of TFIDF-weighted 3-gram
          character counts.