\version "2.13.40"
\header {
  title = "FOLK"
  composer = \markup\bold "Ben CHANTRY "
  instrument = "Bass Bb"
}
\paper {
  page-count = #1
}

bass = \relative c {
  \tempo 4 = 100
  \time 2/2
  \clef bass
  \key bes \major
  \set Score.barNumberVisibility = #all-bar-numbers-visible
  \bar ""
  \override Score.BarNumber #'break-visibility = #' #(#f #t #t)

  \set Score.markFormatter = #format-mark-box-letters
  \override MultiMeasureRest #'expand-limit = #1
  %mesure 1
  r1\mark\default 

  \repeat volta 4 {        
    bes'4  r f r
    bes bes bes r
    bes r f r
  }
  \alternative {
    {f r bes r }
    {f8-- f4-. f8-- bes4-. r}
  }
  \mark\default
  \repeat volta 2 {
    bes r f r
    bes bes bes r
    bes r f r
    f r bes r
  }
  \bar"|."
}

\score {
  \unfoldRepeats {
    \bass
  }
}
 
\score {
  \new Staff {  
    \set Staff.instrumentName = \markup {"Tuba"}
    \set Staff.midiInstrument = "tuba" \bass
  }
  \layout {}
  \midi {}
}