mum needed by the Dvi class.

    Parameters
    ----------
    filename : str or path-like

    Attributes
    ----------
    checksum : int
       Used for verifying against the dvi file.
    design_size : int
       Design size of the font (unknown units)
    width, height, depth : dict
       Dimensions of each character, need to be scaled by the factor
       specified in the dvi file. These are dicts because indexing may
       not start from 0.
    )