function lookup( $state, $la ){
		if( ! isset($this->table[$state][$la]) ){
			return null;
		}	
		else {
			return $this->table[$state][$la];
		}
	}
function lookup( $state, $la ){
		if( ! isset($this->table[$state][$la]) ){
			return null;
		}	
		else {
			return $this->table[$state][$la];
		}
	}
function lookup ( $ state , $ la ) { if ( ! isset ( $ this -> table [ $ state ] [ $ la ] ) ) { return null ; } else { return $ this -> table [ $ state ] [ $ la ] ; } }
Lookup action by state and lookahead symbol
@param int odd-numbered state id
@param mixed look ahead symbol
@return int either an even-numbered rule id, or an odd-numbered state id, or null
Lookup action by state and lookahead symbol