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