<p>In the impossible level, the challenge has been re-written, only to allow a very stricted input. If this doesn't match and doesn't produce a certain result,
it will not be allowed to execute. Rather than "black listing" filtering (allowing any input and removing unwanted), this uses "white listing" (only allow certain values).</p>
<p>
This level is an update of the high level where the JSONP call has its callback function hardcoded and the CSP policy is locked down to only allow external scripts.
