  
          for field_name in field_names:
              if field_name in declared_fields:
                  fields[field_name] = declared_fields[field_name]
                  continue
  
              # Determine the serializer field class and keyword arguments.
              field_class, field_kwargs = self.build_field(
 
</s> remove                 # Field is explicitly declared on the class, use that.
                ret[field_name] = declared_fields[field_name]
 </s> add                 fields[field_name] = declared_fields[field_name] </s> remove             field_cls, kwargs = self.build_field(field_name, info, model, depth)
 </s> add             field_class, field_kwargs = self.build_field(
                field_name, info, model, depth
            ) </s> remove         # Now determine the fields that should be included on the serializer.
        ret = OrderedDict()
 </s> add         # Determine the fields that should be included on the serializer.
        fields = OrderedDict()
 </s> remove             # Populate any kwargs defined in `Meta.extra_kwargs`
            kwargs = self.build_field_kwargs(kwargs, extra_kwargs, field_name)
 </s> add             # Include any kwargs defined in `Meta.extra_kwargs`
            field_kwargs = self.build_field_kwargs(
                field_kwargs, extra_kwargs, field_name
            ) </s> remove             ret[field_name] = field_cls(**kwargs)
 </s> add             fields[field_name] = field_class(**field_kwargs)
            # If the field is explicitly declared on the class then use that.
  
          for field_name in field_names:
            # If the field is explicitly declared on the class then use that.
              if field_name in declared_fields:
                  fields[field_name] = declared_fields[field_name]
                  continue
  
              # Determine the serializer field class and keyword arguments.
              field_class, field_kwargs = self.build_field(
keep add keep keep keep keep keep keep
 Final bits of docs for ModelSerializer fields API 
rest_framework/serializers.py