code: def _len_lcs(x, y):
      """
      Returns the length of the Longest Common Subsequence between sequences x
      and y.
      Source: http://www.algorithmist.com/index.php/Longest_Common_Subsequence
  
      Args:
        x: sequence of words
        y: sequence of words
  
      Returns
        integer: Length of LCS between x and y
      """
      table = _lcs(x, y)
      n, m = len(x), len(y)
      return table[n, m]
  
file_path: seq2seq/seq2seq/metrics/rouge.py
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  from __future__ import unicode_literals
  import itertools
  import numpy
label_desc: Use image node_id 4 for calling a global function with example usage: _len_lcs(x, y) and returns: table