Vertical spacing inside the music

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Hello. I'm looking for the "right" way to control vertical spacing 
within music. The example below doesn't work. Now I know only explicit 
vertical spacing via NonMusicalPaperColumn, and dirty hacks like a very 
low invisible note.

<<
    \new Staff {
        c' c' c' c'
        \override 
Score.VerticalAxisGroup.staff-staff-spacing.basic-distance = #20
        c' c' c' c'
    }
    \new Staff { c' c' c' c' c' c' c' c' }
>>