code: def __call__(self, document, sentences_count):
      self._ensure_dependecies_installed()
  
      dictionary = self._create_dictionary(document)
      # empty document
      if not dictionary:
          return ()
  
      matrix = self._create_matrix(document, dictionary)
      matrix = self._compute_term_frequency(matrix)
      u, sigma, v = singular_value_decomposition(
          matrix, full_matrices=False
      )
  
      ranks = iter(self._compute_ranks(sigma, v))
      return self._get_best_sentences(
          document.sentences, sentences_count, lambda s: next(ranks)
      )
  
file_path: sumy/sumy/summarizers/lsa.py
imports: from __future__ import absolute_import
  from __future__ import division, print_function, unicode_literals
  import math
  from warnings import warn
  from ._summarizer import AbstractSummarizer
label_desc: Use image node_id 3 for calling the LsaSummarizer obj's underlying member method code with example usage: obj.__call__(document, sentences_count) and returns: self, 