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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def normalize_val(self, value=_nothing):
 """Hook which is called on every value before comparison, and should return the scrubbed value or ``self._nothing`` to indicate that the value is not set. """

        if isinstance(value, basestring):
            value = self.normalize_text(value)
        if self.ignore_empty_slots and self.value_is_empty(value):
            value = _nothing
        return value