  class Field(object):
      _creation_counter = 0
  
      default_error_messages = {
          'required': _('This field is required.'),
          'null': _('This field may not be null.')
      }
      default_validators = []
      default_empty_html = empty
      initial = None
  
 
</s> remove         'blank': _('This field may not be blank.'),
        'max_length': _('Ensure this field has no more than {max_length} characters.'),
        'min_length': _('Ensure this field has at least {min_length} characters.')
 </s> add         'blank': _("This field may not be blank."),
        'max_length': _("Ensure this field has no more than {max_length} characters."),
        'min_length': _("Ensure this field has at least {min_length} characters.") </s> remove         'required': _('This field is required.'),
 </s> add         'required': _("This field is required."), </s> remove     missing_message = _('This field is required.')
 </s> add     missing_message = _("This field is required.") </s> remove     message = _('This field must be unique.')
 </s> add     message = _("This field must be unique.") </s> remove     message = _('This field must be unique for the "{date_field}" date.')
 </s> add     message = _("This field must be unique for the \"{date_field}\" date.")
        'required': _("This field is required."),
        'null': _("This field may not be null.")
  class Field(object):
      _creation_counter = 0
  
      default_error_messages = {
        'required': _("This field is required."),
        'null': _("This field may not be null.")
        'required': _("This field is required."),
        'null': _("This field may not be null.")
      }
      default_validators = []
      default_empty_html = empty
      initial = None
  
keep keep keep keep replace replace keep keep keep keep keep
 use double quotes for user visible strings; end user visible strings in full stops; add some missing translation tags 
rest_framework/fields.py