Python 3.9 is now generally available.

google.appengine.api.memcache.set

Sets a key's value, regardless of previous contents in cache.

Unlike add() and replace(), this method always sets (or overwrites) the value in memcache, regardless of previous contents.

key Key to set. See docs on Client for details.
value Value to set. Any type. If complex, will be pickled.
time Optional expiration time, either relative number of seconds from current time (up to 1 month), or an absolute Unix epoch time. By default, items never expire, though items may be evicted due to memory pressure. Float values will be rounded up to the nearest whole second.
min_compress_len Ignored option for compatibility.
namespace a string specifying an optional namespace to use in the request.

True if set. False on error.