\version "2.19"

<<
\new Staff \relative c'' { a4 a a \key a \major s a a }
\new Staff \relative c'' { a4 a a \key a \major a a a }
>>

<<
\new Staff \relative c'' { a4 a a \key a \major r a a }
\new Staff \relative c'' { a4 a a \key a \major a a a }
>>

<<
\new Staff \relative c'' { a4 a a \key a \major \hideNotes r \unHideNotes a a }
\new Staff \relative c'' { a4 a a \key a \major a a a }
>>

<<
\new Staff \relative c'' { a4 a a \key a \major a a a }
\new Staff \relative c'' { a4 a a \key a \major s a a }
>>

<<
\new Staff \relative c'' { a4 a a \key a \major a a a }
\new Staff \relative c'' { a4 a a \key a \major a a a }
>>

<<
\new Staff \relative c'' { a4 a a \key a \major s a a }
>>