old_contents: import sys
  
  
  def is_int(number):
      if sys.version_info[0] == 2:
          return isinstance(number, (int, long))
      else:
          return isinstance(number, int)
  
new_contents: import sys
  
  
  def is_int(number):
      if sys.version_info[0] == 2:
          return isinstance(number, (int, long))
      else:
          return isinstance(number, int)
  
  
  def is_string(value):
      if sys.version_info[0] == 2:
          return isinstance(value, (str, unicode))
      else:
          return isinstance(value, (bytes, str))
  
subject: Add `is_string()` function