code: def _gcd(a, b):
      """Calculate the greatest common divisor of a and b"""
      while b:
          a, b = b, a % b
      return a
  
imports: import ast
  import re
  import sys
  import warnings
  from ..exceptions import DTypePromotionError
  from .multiarray import dtype, array, ndarray, promote_types
label_desc: Use image node_id 16 for calling a global function with example usage: _gcd(a, b) and returns: a