o<extend_m9> sub
o2 if [#<_task> EQ 1]
 o1 if [EXISTS [#<P>]]
  (DEBUG,M9 P-word passed: #<P>)
 o1 else
  (DEBUG,M9 No P-word passed)
 o1 endif
 m9 (call built-in m9)
 (DEBUG, extend_m9 done)
o2 endif
o<extend_m9> endsub
m2
