\version "2.19.36"

\markup "Default up-stem, with three beams"

\relative c' {
  \time 2/4
  a32 [ a a a ]

  b [ b b b ]

  c c c c

  \once \override Beam.color = #red
  d [ d d d ]

  e e e e

  \once \override Beam.color = #red
  f [f f f ]
  g g g g

  \once \override Beam.color = #red
  a [ a a a ]
  
  \stemUp
  \once \override \Beam.color = #red
  b [ b b b ]
}

\markup "Corrected up-stem, with three beams"

\relative a {
  \time 2/4
  a32 [ a a a ]
  b [ b b b ]
  c c c c

  \once \override Beam.color = #blue
  \override Stem.details.beamed-lengths = #'(4.5)
  d [ d d d ]

  \revert Stem.details.beamed-lengths
  e e e e

  \once \override Beam.color = #blue
  \override Stem.details.beamed-lengths = #'(4.5)
  f [f f f ]

  \revert Stem.details.beamed-lengths
  g g g g

  \once \override Beam.color = #blue
  \override Stem.details.beamed-lengths = #'(4.5)
  a [ a a a ]
  
  \stemUp
  \once \override Beam.color = #blue
  \override Stem.details.beamed-lengths = #'(4)
  b [ b b b ]
}

\markup "Default up-stem, with four beams"

\relative c' {
  \time 2/4
  a64 [ a a a ]

  b [ b b b ]

  c c c c

  \once \override Beam.color = #red
  d [ d d d ]

  e e e e

  \once \override Beam.color = #red
  f [f f f ]
  g g g g

  \once \override Beam.color = #red
  a [ a a a ]
  
  \stemUp
  \once \override Beam.color = #red
  b [ b b b ]
}

\markup "Corrected up-stem, with four beams"

\relative a {
  \time 2/4
  a64 [ a a a ]
  b [ b b b ]
  c c c c

  \once \override Beam.color = #blue
  \override Stem.details.beamed-lengths = #'(5.5)
  d [ d d d ]

  \revert Stem.details.beamed-lengths
  e e e e

  \once \override Beam.color = #blue
  \override Stem.details.beamed-lengths = #'(5.5)
  f [f f f ]

  \revert Stem.details.beamed-lengths
  g g g g

  \once \override Beam.color = #blue
  \override Stem.details.beamed-lengths = #'(5.5)
  a [ a a a ]
  
  \stemUp
  \once \override Beam.color = #blue
  \override Stem.details.beamed-lengths = #'(5)
  b [ b b b ]
}

\markup "Default down-stem, with three beams"

\relative b' {
  \time 2/4
  \once \override Beam.color = #red
  b32 b b b

  \once \override Beam.color = #red
  c [ c c c ]

  d [ d d d ]

  \once \override Beam.color = #red
  e e e e

  f [ f f f ]

  \once \override Beam.color = #red
  g g g g

  a [a a a ]

  b b b b

  c [ c c c ]
}

\markup "Corrected down-stem, with three beams"

\relative b' {
  \time 2/4
  \once \override Beam.color = #blue
  \override Stem.details.beamed-lengths = #'(4)
  b32 b b b

  \once \override Beam.color = #blue
  \override Stem.details.beamed-lengths = #'(4.5)
  c [ c c c ]

  \revert Stem.details.beamed-lengths
  d [ d d d ]

  \once \override Beam.color = #blue
  \override Stem.details.beamed-lengths = #'(4.5)
  e e e e

  \revert Stem.details.beamed-lengths
  f [ f f f ]

  \once \override Beam.color = #blue
  \override Stem.details.beamed-lengths = #'(4.5)
  g g g g

  \revert Stem.details.beamed-lengths
  a [a a a ]

  b b b b

  c [ c c c ]
}

\markup "Default down-stem, with four beams"

\relative b' {
  \time 2/4
  \once \override Beam.color = #red
  b64 b b b

  \once \override Beam.color = #red
  c [ c c c ]

  d [ d d d ]

  \once \override Beam.color = #red
  e e e e

  f [ f f f ]

  \once \override Beam.color = #red
  g g g g

  a [a a a ]

  b b b b

  c [ c c c ]
}

\markup "Corrected down-stem, with four beams"

\relative b' {
  \time 2/4
  \once \override Beam.color = #blue
  \override Stem.details.beamed-lengths = #'(5)
  b64 b b b

  \once \override Beam.color = #blue
  \override Stem.details.beamed-lengths = #'(5.5)
  c [ c c c ]

  \revert Stem.details.beamed-lengths
  d [ d d d ]

  \once \override Beam.color = #blue
  \override Stem.details.beamed-lengths = #'(5.5)
  e e e e

  \revert Stem.details.beamed-lengths
  f [ f f f ]

  \once \override Beam.color = #blue
  \override Stem.details.beamed-lengths = #'(5.5)
  g g g g

  \revert Stem.details.beamed-lengths
  a [a a a ]

  b b b b

  c [ c c c ]
}