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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 setSizeMetadata(self, size):
 """ Set size image metadata to what has been reliably identified. """

    assert((self.needMetadataUpdate(CoverImageMetadata.SIZE)) or
           (self.size == size))
    self.size = size
    self.check_metadata &= ~CoverImageMetadata.SIZE