Update validators.py

 - Add Docstring
 - Add default message

baseframe/forms/validators.py

@@ -300,6 +300,22 @@ class NotEqualTo(_Comparison):
     def compare(self, value, other):
         return value != other
 
+class IsEmoji(object):
+    """
+    Validate that field.data does not belong to a public email domain.
+    If the domain lookup fails and mxsniff raises ``MXLookupException``, this validator
+    will still pass, as we expect that most domains are not public email domains.
+
+    :param message:
+        Error message to raise in case of a validation error.
+    """
+    def __init__(self, message=None):
+        self.message = message or _(u'This is not a valid emoji.')
+
+    def __call__(self, form, field):
+        if not field.data in emoji.UNICODE_EMOJI:
+            raise ValidationError(self.message)
+
 
 class IsPublicEmailDomain(object):
     """
@@ -321,15 +337,6 @@ def __call__(self, form, field):
         else:
             raise ValidationError(self.message)
 
-class IsEmoji(object):
-
-    def __init__(self, message=None):
-        self.message = message
-
-    def __call__(self, form, field):
-        if not field.data in emoji.UNICODE_EMOJI:
-            raise ValidationError(self.message)
-
 
 class IsNotPublicEmailDomain(object):
     """