  
  @six.add_metaclass(SerializerMetaclass)
  class Serializer(BaseSerializer):
      default_error_messages = {
          'invalid': _("Invalid data. Expected a dictionary, but got {datatype}.")
      }
  
      @property
      def fields(self):
          """
 
</s> remove         'not_a_list': _("Expected a list of items but got type `{input_type}`.")
 </s> add         'not_a_list': _('Expected a list of items but got type `{input_type}`.') </s> remove         'invalid': _("Enter a valid email address.")
 </s> add         'invalid': _('Enter a valid email address.') </s> remove         'does_not_exist': _("Object with {slug_name}={value} does not exist."),
        'invalid': _("Invalid value."),
 </s> add         'does_not_exist': _('Object with {slug_name}={value} does not exist.'),
        'invalid': _('Invalid value.'), </s> remove         'invalid': _("`{input}` is not a valid boolean.")
 </s> add         'invalid': _('`{input}` is not a valid boolean.') </s> remove         'invalid': _("`{input}` is not a valid boolean.")
 </s> add         'invalid': _('`{input}` is not a valid boolean.')
        'invalid': _('Invalid data. Expected a dictionary, but got {datatype}.')
  
  @six.add_metaclass(SerializerMetaclass)
  class Serializer(BaseSerializer):
      default_error_messages = {
        'invalid': _('Invalid data. Expected a dictionary, but got {datatype}.')
      }
  
      @property
      def fields(self):
          """
keep keep keep keep replace keep keep keep keep keep
 prefer single quotes in source and double quotes in user visible strings; add some missing full stops to user visible strings 
rest_framework/serializers.py