Verify that value is a valid version specifier

def check_specifier(dist, attr, value):
    """Verify that value is a valid version specifier"""
    try:
        packaging.specifiers.SpecifierSet(value)
    except packaging.specifiers.InvalidSpecifier as error:
        tmpl = (
            "{attr!r} must be a string "
            "containing valid version specifiers; {error}"
        )
        raise DistutilsSetupError(tmpl.format(attr=attr, error=error))