def _gendesc(infiles):
    """
    Generate a desc entity value.

    Examples
    --------
    >>> _gendesc("f")
    'coeff'

    >>> _gendesc(list("ab"))
    ['coeff0', 'coeff1']

    """
    if isinstance(infiles, (str, bytes)):
        infiles = [infiles]

    if len(infiles) == 1:
        return "coeff"

    return [f"coeff{i}" for i, _ in enumerate(infiles)]