[1.6.x] Removed a mention of `Form._errors` from the documentation.

  cleaned data if you override this method (by default, ``Form.clean()``

  just returns ``self.cleaned_data``).

  Since the field validation methods have been run by the time ``clean()`` is

  called, you also have access to the form's errors attribute which

  contains all the errors raised by cleaning of individual fields.

  Note that any errors raised by your ``Form.clean()`` override will not

  be associated with any field in particular. They go into a special

  "field" (called ``__all__``), which you can access via the

for each field in the form (in the order they are declared in the form

definition), the ``Field.clean()`` method (or its override) is run, then

``clean_<fieldname>()``. Finally, once those two methods are run for every

field, the ``Form.clean()`` method, or its override, is executed.

field, the ``Form.clean()`` method, or its override, is executed whether or not

the previous methods have raised errors.

Examples of each of these methods are provided below.

field-specific cleaning method is not called. However, the cleaning methods

for all remaining fields are still executed.

The ``clean()`` method for the ``Form`` class or subclass is always run. If

that method raises a ``ValidationError``, ``cleaned_data`` will be an empty

dictionary.

The previous paragraph means that if you are overriding ``Form.clean()``, you

should iterate through ``self.cleaned_data.items()``, possibly considering the

``_errors`` dictionary attribute on the form as well. In this way, you will

already know which fields have passed their individual validation requirements.

.. _raising-validation-error:

Raising ``ValidationError``