my $rx_days = qr{ (?i)  # custom patterns
        .*? \K \b mo (?: n (?: day)?)?                 |
        .*? \K \b tu (?: e (?: s (?: day)?)?)?         |
        .*? \K \b we (?: d (?: nes day)?)?             |
        .*? \K \b th (?: u (?: r (?: s (?: day)?)?)?)? |
        .*? \K \b fr (?: i (?: day)?)?                 |
        .*? \K \b sa (?: t (?: ur day)?)?              |
        .*? \K \b su (?: n (?: day)?)?
        }xms;