old_contents: def gcd(m, n):
      """Greatest Common Divisor (GCD) by Euclid's Algorithm.
  
      Time complexity: O(m%n).
      """
      while n != 0:
          m, n = n, m % n
      return m
  
  
  def main():
      print(gcd(4, 2))
      print(gcd(2, 4))
  
      print(gcd(10, 4))
      print(gcd(4, 10))
  
      print(gcd(10, 1))
      print(gcd(1, 10))
  
  
  if __name__ == '__main__':
      main()
  
new_contents: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  
  
  def gcd(m, n):
      """Greatest Common Divisor (GCD) by Euclid's Algorithm.
  
      Time complexity: O(m%n).
      """
      while n != 0:
          m, n = n, m % n
      return m
  
  
  def main():
      print('gcd(4, 2): {}'.format(gcd(4, 2)))
      print('gcd(2, 4): {}'.format(gcd(2, 4)))
  
      print('gcd(10, 4): {}'.format(gcd(10, 4)))
      print('gcd(4, 10): {}'.format(gcd(4, 10)))
  
      print('gcd(3, 4): {}'.format(gcd(3, 4)))
      print('gcd(4, 3): {}'.format(gcd(4, 3)))
  
  
  if __name__ == '__main__':
      main()
  
subject: Add importing from __future__ & revise main()