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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 diff(self):
 """Determines if changes are needed for the Vault backend"""


        if not self.present:
            if self.existing:
                return DEL

            return NOOP

        is_diff = NOOP
        if self.present and self.existing:
            a_obj = self.config.copy()
            if self.config and diff_dict(a_obj, self.existing, True):
                is_diff = CHANGED

            if self.description != self.existing.get('description'):
                is_diff = CONFLICT

        elif self.present and not self.existing:
            is_diff = ADD

        return is_diff