Yea, it's kinda nested; this UMD wrapper, if it doesn't detect AMD or CommonJS, uses the `this` of the caller, which, in the case of a browser is `window`. On [line 51](https://github.com/novus/nvd3/pull/556/files#diff-c28725a3f01bd414e172f44db61b713dR51) below, it attaches `nv` to window.