I'm pretty sure this is cheating, but...

  #!/bin/sh
  grep -e "g\(()\)*('al')" $0 | sed 's/()/o/g' | sed "s/('al')/al/"
  exit
  g()('al')

On its own, g()('al') is valid but g()()('al') is a syntax error. Also, bash and sh don't have non-numeric return values, so regardless of the solution you're stuck with printing.