code: def levenshtein(a, b):
      "Calculates the Levenshtein distance between a and b."
      n, m = len(a), len(b)
      if n > m:
          # Make sure n <= m, to use O(min(n,m)) space
          a, b = b, a
          n, m = m, n
  
      current = list(range(n + 1))
      for i in range(1, m + 1):
          previous, current = current, [i] + [0] * n
          for j in range(1, n + 1):
              add, delete = previous[j] + 1, current[j - 1] + 1
              change = previous[j - 1]
              if a[j - 1] != b[i - 1]:
                  change = change + 1
              current[j] = min(add, delete, change)
  
      return current[n]
  
imports: from __future__ import absolute_import, division, print_function
  import numpy
  import struct
label_desc: Use image node_id 2 for calling a global function with example usage: levenshtein(a, b) and returns: current