def get_rb_data_attribute(xmldict, attr):
    """Get Attribute `attr` from dict `xmldict`

    Parameters
    ----------
    xmldict : dict
        Blob Description Dictionary
    attr : string
        Attribute key

    Returns
    -------
    sattr : int
        Attribute Values
    """
    try:
        sattr = int(xmldict['@' + attr])
    except KeyError:
        raise KeyError(
            'Attribute @{0} is missing from Blob Description. There may be some problems with your file'
            .format(attr))
    return sattr
