Putting parentheses around a single note

Objects may be parenthesized by prefixing \parenthesize to the music event: in other words, the note has to be put after the \parenthesize command.

This only functions inside chords; to parenthesize a single note it must be enclosed with <> as if it is a chord.

\version "2.24"

%% http://lsr.di.unimi.it/LSR/Item?id=318

\relative c'' {
  a4
  < \parenthesize b >
  c d
}