\property Voice.Stem \set #'direction = #-1
\property Voice.Tie \set #'direction = #-1
\property Voice.Slur \set #'direction = #-1
\property Voice.Slur \set #'attachment = #'(head . head)
\property Voice.Stem \set #'direction = #-1
\property Voice.Tie \set #'direction = #-1
\property Voice.Slur \set #'direction = #-1
\property Voice.Slur \set #'attachment = #'(head . head)