distance between lines in custom markup

[Adam Good]

Hi everyone,

in the markup below, two lines of text will be printed in a column  
so, one on top of the other.

How can I decrease/increase the vspace between them?

Thanks all

Adam Good

%%%%%
custommark =
#(define-music-function (parser location marktext) (string?)
 (make-music 'TextScriptEvent
  'direction 1
  'text (markup #:column (#:line (#:small #:italic "Some Text")
#:small #:italic #:line (marktext)))))
%%%%%