( Native words )
H@ 4 + XCURRENT ! ( make next CODE have 0 prev field )
CODE (br) ( TODO: move with other native words )
L1 BSET ( used in ?br and loop )
PC ORG @ 0x3d + ! ( stable ABI JP )
    E 0 IY+ LDrIXY, D 1 IY+ LDrIXY,
    DE ADDIYd,
;CODE
CODE (?br)
PC ORG @ 0x41 + ! ( stable ABI JP )
    HL POP,
    HLZ,
    JRZ, L1 BWR ( br + 1. False, branch )
    ( True, skip next 2 bytes and don't branch )
    IY INCd, IY INCd,
;CODE