%% http://lsr.di.unimi.it/LSR/Item?id=134

\score {
  \new PianoStaff
  <<
    \context Staff = "up" {
      \clef bass
      s1 * 4
    } 
    \context Staff = "down" \relative c 
    <<
      s1*4
      {
        \clef bass
        r4 r8
        \vshape #'((-0.5 . -3) (10 . 2) (-25 . -20) (-0.5 . -6)) Slur
        c8( as' f c' as
        
        % line breaks will mess up this example  
        \noBreak
        f f,, as'' f
        \change Staff = up
        \clef treble
        c' as f' c
        \noBreak
        as' f c' as
        f' c as' f c'4)
      }
    >>
  >>
  \layout { }
}