code: def DictKeys(keys):
      
      req = [(Key(key), Any) for key in keys]
      return Dict(dict(req))
docs: Checks if dict has all given keys
  
      :param keys:
      :type keys:
  
      >>> _dd(DictKeys(['a','b']).check({'a':1,'b':2,}))
      "{'a': 1, 'b': 2}"
      >>> extract_error(DictKeys(['a','b']), {'a':1,'b':2,'c':3,})
      {'c': 'c is not allowed key'}
      >>> extract_error(DictKeys(['key','key2']), {'key':'val'})
      {'key2': 'is required'}