def read_metadata(self, handler):
        self.metadata = handler.read_metadata(self.cname)
Compute the display position for a new FileAttachmentHistory.
dataset/ETHPy150Open pydata/pandas/pandas/io/pytables.py/IndexCol.read_metadata--crossover with--dataset/ETHPy150Open reviewboard/reviewboard/reviewboard/attachments/models.py/FileAttachmentHistory.compute_next_display_position