def build_diff_filename(name, ver_old, ver_new):
    """ Returns filename for an abidiff content
    Parameters:
        name(str): package spec name
        old(str): old version
        new(str): new version
    """
    bad_ch = ["/"]
    for c in bad_ch:
        ver_old = ver_old.replace(c, "")
        ver_new = ver_new.replace(c, "")
    fn = "{}__{}__{}.abidiff".format(name, ver_old, ver_new)
    return fn