Some PIR code for handling expression tokens

optable = get_hll_global [ 'ABC::Grammar' ], '$optable'
optok = optable[type]
pasttype = optok['past']
pirop = optok['pirop']
returns = optok['returns']
islvalue = optok['lvalue']

.local pmc past, iter
past = new 'PAST::Op'
past.'init'('node'=>node, 'name'=>type, 'pasttype'=>pasttype, 
            'pirop'=>pirop, 'returns'=>returns)