  
      flatten_choices_dict({1: '1st', 2: '2nd'}) -> {1: '1st', 2: '2nd'}
      flatten_choices_dict({'Group': {1: '1st', 2: '2nd'}}) -> {1: '1st', 2: '2nd'}
      """
      ret = OrderedDict()
      for key, value in choices.items():
          if isinstance(value, dict):
              # grouped choices (category, sub choices)
              for sub_key, sub_value in value.items():
                  ret[sub_key] = sub_value
 
</s> remove         expected = OrderedDict([(1, 'Red Color'), (2, 'Yellow Color'), (3, 'Green Color')])
 </s> add         expected = {1: 'Red Color', 2: 'Yellow Color', 3: 'Green Color'} </s> remove         expected = OrderedDict([(1, 'My Red Color'), (2, 'My Yellow Color'), (3, 'My Green Color')])
 </s> add         expected = {1: 'My Red Color', 2: 'My Yellow Color', 3: 'My Green Color'} </s> remove     ret = OrderedDict()
 </s> add     ret = {} </s> remove         ret = OrderedDict()
 </s> add         ret = {} </s> remove         errors = OrderedDict()
 </s> add         errors = {}
    ret = {}
  
      flatten_choices_dict({1: '1st', 2: '2nd'}) -> {1: '1st', 2: '2nd'}
      flatten_choices_dict({'Group': {1: '1st', 2: '2nd'}}) -> {1: '1st', 2: '2nd'}
      """
    ret = {}
      for key, value in choices.items():
          if isinstance(value, dict):
              # grouped choices (category, sub choices)
              for sub_key, sub_value in value.items():
                  ret[sub_key] = sub_value
keep keep keep keep replace keep keep keep keep keep
 Replaced `OrderedDict` with `dict` (#8964) 
rest_framework/fields.py