duration and pitch in a function

[Paolo Prete]

Hi,

I need to create a function that

accepts  some_pitch and some_duration as arguments and prints the following 
three notes:   

1) some_pitch with some_duration
2) some_pitch with some_duration*2
3) some_pitch with some_duration*3


Should I use ly:duration as type of the argument two? I can't find 
documentation for that. 

I use LilyPond 2.12.3 but I can upgrade it if necessary...

thanks