Function multi_line_flags 

pub fn multi_line_flags(
    sig: &str,
    m: &PySigMatch,
    opts: SingleLineOpts,
    cfg: &PySigConfig,
) -> (bool, bool)

The (multi_line_parameter_list, multi_line_type_parameter_list) pair (_object.py:300-311, [SIG §1.3]): each flag is !single-line-option && (len(sig) - width(other group)) > max_len > 0, strictly greater, with max_len resolved by PySigConfig::max_len. Lengths are Python len() — Unicode scalar counts — computed from the byte spans’ slices; an out-of-range span counts as width 0.