new_contents: import json
  import hashlib
  
  def __sum_list(o):
          buf = ''
          if type(o) is not list:
                  raise ValueError('must be a list')
          for i in sorted(o):
                  if type(i) is dict:
                          buf += __sum_dict(i)
                  elif type(i) is list:
                          buf += __sum_list(i)
                  else:
                          buf += "{}".format(i)
          return buf
  
  def __sum_dict(o):
          buf = ''
          if type(o) is not dict:
                  raise ValueError('must be a dict')
          for key in sorted(o):
                  if type(o[key]) is dict:
                          buf += "{}{}".format(key, __sum_dict(o[key]))
                  elif type(o[key]) is list:
                          buf += "{}{}".format(key, __sum_list(o[key]))
                  else:
                          buf += "{}{}".format(key, o[key])
          return buf
  
  def check_sum_object_issue(o):
          ''' return [[true|false], sha1-sum] '''
          buf = ''
          if type(o) is not dict:
                  return [False, None]
          # check if required attributes are all available
          if "title" not in o: return [False, None]
          if "description" not in o: return [False, None]
          if "categories" not in o: return [False, None]
          if "version" not in o: return [False, None]
  
          try:
                  buf = __sum_dict(o)
          except ValueError:
                  return [False, None]
          buf_digest = hashlib.sha1(buf).hexdigest()
          return [True, buf_digest]
  
subject: add functionality to hash things