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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 merge(self, other):
 """ Merges two strings """

        other = StringCell.coerce(other)
        if self.is_equal(other):
            # pick among dependencies
            return self
        elif other.is_entailed_by(self):
            return self
        elif self.is_entailed_by(other):
            self.value = other.value
        elif self.is_contradictory(other):
            raise Contradiction("Cannot merge string '%s' with '%s'" % \
                    (self, other))
        else:
            self._perform_merge(other)
        return self