Marks the entire flash or a single flash entry to be discarded by the end
of the current action:
flash.discard# discard the entire flash at the end of the current actionflash.discard(:warning)# discard only the "warning" entry at the end of the current action
# File actionpack/lib/action_controller/flash.rb, line 107
def discard(k = nil)
use(k)
end
