It said "never incur request or bandwidth charges". I assume this means you don't pay to compute the response or for the bandwidth to deliver it.
Seems you could compute the response, store it somewhere (memcached or something), and then return an error. Then have the caller make another call to retrieve the response. (To associate the two requests, have the caller generate a UUID and pass it on both calls.)
That doesn't make it entirely free, but it reduces the compute cost of every request to just reading from a cache.
(This does sound like a good way to get banned or something else nasty, so it's definitely not a recommendation.)
Seems you could compute the response, store it somewhere (memcached or something), and then return an error. Then have the caller make another call to retrieve the response. (To associate the two requests, have the caller generate a UUID and pass it on both calls.)
That doesn't make it entirely free, but it reduces the compute cost of every request to just reading from a cache.
(This does sound like a good way to get banned or something else nasty, so it's definitely not a recommendation.)