Hammer-on and pull-off using voices

The arc of hammer-on and pull-off is upwards in voices one and three and downwards in voices two and four:

\version "2.24"

\new TabStaff {
  \relative c' {
    << { \voiceOne g2( a) }
    \\ { \voiceTwo a,( b) }
    >> \oneVoice
  }
}