If the message is understood by {TAIL ~ the referenced object}, then {HEAD ~ the method} is executed in accordance with the message sent, and operation is completed as to the particular message 
If the message is understood by { TAIL ~ the referenced object } , then { HEAD ~ the method } is executed in accordance with the message sent , and operation is completed as to the particular message
OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH