Transposition

[Tom van der Hoeven]

I have a piece of music written in different transpositions.

I want to transform it to a piece in one transposition.

I have found \transposition to indicate the transposition of the 
subsequent notes.

trap = \relative c'{ a \transposition f'  c e g f bes \transposition 
bes' c e}

It is used for Midi and quotations, where the music is based on the 
concert pitch

I could not find a general command to bring a piece to the common 
concert pitch.

Something like AAA = \ctransform{trap} where AAA can be used in a \score

It seems the functionality is there, so I must have overlooked something.