Various helpers for interacting with registers from inside a VM callback implementations
func getBool(a: VmArgs; i: Natural): bool {....raises: [], tags: [].}
func getFloat(a: VmArgs; i: Natural): BiggestFloat {....raises: [], tags: [].}
func getHandle(a: VmArgs; i: Natural): LocHandle {....raises: [], tags: [].}
func getInt(a: VmArgs; i: Natural): BiggestInt {....raises: [], tags: [].}
func getNode(a: VmArgs; i: Natural): PNode {....raises: [], tags: [].}
func getResultHandle(a: VmArgs): LocHandle {....raises: [], tags: [].}
func getString(a: VmArgs; i: Natural): string {....raises: [], tags: [].}
proc getVar(a: VmArgs; i: Natural): LocHandle {....raises: [], tags: [].}
proc numArgs(a: VmArgs): int {....raises: [], tags: [].}
proc setResult(a: VmArgs; v: AbsoluteDir) {....raises: [], tags: [].}
proc setResult(a: VmArgs; v: BiggestFloat) {....raises: [], tags: [].}
proc setResult(a: VmArgs; v: BiggestInt) {....raises: [], tags: [].}
proc setResult(a: VmArgs; v: bool) {....raises: [], tags: [].}
proc setResult(a: VmArgs; v: openArray[char]) {....raises: [], tags: [].}
proc setResult(a: VmArgs; v: PNode) {....raises: [], tags: [].}