def clean(self, value, model_instance):
value = self.to_python(value)<EOL>if value is not None:<EOL><INDENT>value = self.get_sanitizer()(value)<EOL><DEDENT>self.validate(value, model_instance)<EOL>self.run_validators(value)<EOL>return value<EOL>
Convert the value's type, sanitize it, and run validation. Validation
errors from to_python() and validate() are propagated. Return the
correct value if no error is raised.