code: def random_string(length, chars=None):
      import string
  
      if chars is None:
          chars = list(
              string.ascii_letters
              + string.ascii_letters
              + "()[]+-.=#@/\\"
          )
      return "".join(np.random.choice(chars, length))
  
file_path: deepchem/deepchem/utils/test/test_hash_utils.py
imports: import unittest
  import numpy
  from deepchem.utils import hash_utils
label_desc: Use image node_id 1 for calling a global function with example usage: random_string(length, chars) and returns: str