code: def gcd(a, b):
      """Computes the greatest common divisor of integers a and b using
      Euclid's Algorithm.
      gcd{𝑎,𝑏}=gcd{−𝑎,𝑏}=gcd{𝑎,−𝑏}=gcd{−𝑎,−𝑏}
      See proof: https://proofwiki.org/wiki/GCD_for_Negative_Integers
      """
      a_int = isinstance(a, int)
      b_int = isinstance(b, int)
      a = abs(a)
      b = abs(b)
      if not (a_int or b_int):
          raise ValueError("Input arguments are not integers")
  
      if (a == 0) or (b == 0):
          raise ValueError("One or more input arguments equals zero")
  
      while b != 0:
          a, b = b, a % b
      return a
  
label_desc: Use image node_id 1 for calling a global function with example usage: gcd(a, b) and returns: a