New in version 2.5.
List secondary instruments:
abjad> for secondary_instrument in instrumenttools.list_secondary_instruments():
... secondary_instrument
...
<class 'abjad.tools.instrumenttools.AltoFlute.AltoFlute.AltoFlute'>
<class 'abjad.tools.instrumenttools.AltoTrombone.AltoTrombone.AltoTrombone'>
<class 'abjad.tools.instrumenttools.BaritoneSaxophone.BaritoneSaxophone.BaritoneSaxophone'>
<class 'abjad.tools.instrumenttools.BassClarinet.BassClarinet.BassClarinet'>
<class 'abjad.tools.instrumenttools.BassFlute.BassFlute.BassFlute'>
<class 'abjad.tools.instrumenttools.BassSaxophone.BassSaxophone.BassSaxophone'>
<class 'abjad.tools.instrumenttools.BassTrombone.BassTrombone.BassTrombone'>
<class 'abjad.tools.instrumenttools.ClarinetInA.ClarinetInA.ClarinetInA'>
<class 'abjad.tools.instrumenttools.ContrabassClarinet.ContrabassClarinet.ContrabassClarinet'>
<class 'abjad.tools.instrumenttools.ContrabassFlute.ContrabassFlute.ContrabassFlute'>
<class 'abjad.tools.instrumenttools.ContrabassSaxophone.ContrabassSaxophone.ContrabassSaxophone'>
<class 'abjad.tools.instrumenttools.Contrabassoon.Contrabassoon.Contrabassoon'>
<class 'abjad.tools.instrumenttools.EFlatClarinet.EFlatClarinet.EFlatClarinet'>
<class 'abjad.tools.instrumenttools.EnglishHorn.EnglishHorn.EnglishHorn'>
<class 'abjad.tools.instrumenttools.Glockenspiel.Glockenspiel.Glockenspiel'>
<class 'abjad.tools.instrumenttools.Marimba.Marimba.Marimba'>
<class 'abjad.tools.instrumenttools.Piccolo.Piccolo.Piccolo'>
<class 'abjad.tools.instrumenttools.SopraninoSaxophone.SopraninoSaxophone.SopraninoSaxophone'>
<class 'abjad.tools.instrumenttools.SopranoSaxophone.SopranoSaxophone.SopranoSaxophone'>
<class 'abjad.tools.instrumenttools.TenorSaxophone.TenorSaxophone.TenorSaxophone'>
<class 'abjad.tools.instrumenttools.UntunedPercussion.UntunedPercussion.UntunedPercussion'>
<class 'abjad.tools.instrumenttools.Vibraphone.Vibraphone.Vibraphone'>
<class 'abjad.tools.instrumenttools.Xylophone.Xylophone.Xylophone'>
Return list