The npm package a binding's imports name at runtime, derived from the package the
 declarations were generated from.

 A DefinitelyTyped package ships no JavaScript, so an import that names it resolves to
 nothing at all: `@types/three` carries the types and `three` carries the code. The
 derivation is DefinitelyTyped's own naming convention, which is the only thing on disk
 that says what the runtime is called - a `@types/*` manifest has no field for it:

 - `@types/three` -> `three`;
 - `@types/babel__core` -> `@babel/core`, because DT mangles a scope into the name by
   folding `@scope/name` to `scope__name` (it publishes one flat `@types` scope, so it
   has nowhere else to put the scope);
 - anything not under `@types/` is its own runtime, unchanged.

 The mangling is only ambiguous against an unscoped package whose own name contains
 `__`, which DefinitelyTyped's convention cannot express either; `runtime` in
 `xantham.json` overrides the whole derivation for that and for every other package the
 convention does not describe.