get next argument. Skip past all []s and the BYREF symbol
#IF (!0>0)
#IFADIM !1
DEFINE_NEXT_ARGUMENT !2 !3 !4 !5 !6 !7 !8 !9
#ELSE
#IFSAME !1 BYREF
DEFINE_ARGUMENTS !3 !4 !5 !6 !7 !8 !9
#ELSE
DEFINE_ARGUMENTS !2 !3 !4 !5 !6 !7 !8 !9
#ENDIF
#ENDIF
#ENDIF