Class actions to represent Boolean expressions as trees. Source: 11.js, line 551 Methods and() and: expr 'and' expr; returns [ 'and' a b ] Source: 11.js, line 560 bool() bool: 'true' | 'false'; returns [ 'bool' bool ] Source: 11.js, line 570 not() not: 'not' expr; returns [ 'not' b ] Source: 11.js, line 565 or() or: expr 'or' expr; returns [ 'or' a b ] Source: 11.js, line 555