handler 
infoAt: key 
infoAt: key ifAbsentPut: absentHandler 
infoAt: key put: value 
infoIsReservedKey: key 
infoReserveKey: key 
isReply 
remoteHandler 
sender 
deferReply 
earlyReply: value continuation: continuation 
isAsynchronous 
isDeferred 
lateReply: value 
markAsAsynchronous 