Microsoft MakeCode

shim=ENUM_GET being ignored in api.ts file?

I am getting up to speed on MakeCode/PXT and working through some of the examples. In particular, I am stuck on creating a block that can generate a enum per the playground example (color, flags, planets). In my api.ts file I have the following:

//% shim=ENUM_GET
//% blockId=color_enum_shim
//% block=“Color $arg”
//% enumName=“Colors”
//% enumMemberName=“color”
//% enumPromptHint=“e.g. Green, Orange, …”
//% enumInitialMembers=“Red, Blue, Yellow”
function _colorEnumShim(arg: number) {
return arg
}

and what winds up in the sim.d.ts file in libs/core is:
//% shim=ENUM_GET
//% blockId=color_enum_shim
//% block=“Color $arg”
//% enumName=“Colors”
//% enumMemberName=“color”
//% enumPromptHint=“e.g. Green, Orange, …”
//% enumInitialMembers=“Red, Blue, Yellow”
//% shim=dog::_colorEnumShim
function _colorEnumShim(arg: number): number;

But the block doesn’t act as an enumeration, but rather a function that takes a number and returns a number.

Any help would be greatly appreciated. I am using the latest from github.