code: def test_add_histogram(self):
      if not hasattr(summary, "add_histogram"):
          return
      for i in range(10):
          x = np.random.random(1000)
          summary.add_histogram("distribution_centers", x + i, i)
  
file_path: PARL/parl/utils/tests/summary_test.py
imports: import unittest
  from parl.utils import summary
  import numpy
  from parl.utils import logger
  import os
label_desc: Use image node_id 3 for calling the TestUtils obj's underlying member method code with example usage: obj.test_add_histogram() without return types