code: def ham_dist(str1, str2):
      """Hamming distance. Count the number of differences between str1 and str2."""
      assert len(str1) == len(str2)
      return sum(c1 != c2 for c1, c2 in zip(str1, str2))
  
file_path: pysc2/pysc2/lib/stopwatch_test.py
imports: import os
  from absl.testing import absltest
  import mock
  from pysc2.lib import stopwatch
label_desc: Use image node_id 1 for calling a global function with example usage: ham_dist(str1, str2) and returns: sum