Class actions to represent string expressions as trees. Source: 11.js, line 576 Methods input() input: 'input' [ String String ]; returns [ 'input' unescaped-string unescaped-string ] Source: 11.js, line 580 len() len: 'len' expr; returns [ 'len' b ] Source: 11.js, line 590 string() string: String; returns [ 'string' unescaped-string ] Source: 11.js, line 595