Parameterizing a LilyPond function

[PMA]

Hi List.

I would like to alter this function...

glissmove = {
  \once \override Glissando #'(bound-details left Y) = #1.3
  \once \override Glissando #'(bound-details right Y) = #1.3
}

to accept its 1.3 or whatever as an input parameter instead.

I see docs on parameterizing Scheme functions, but not on
doing this in LilyPond directly -- LP's param handing syntax.
Have I overlooked something obvious?

Thanks in advance.

Pete