refactor: strictly typed

src/parser/delimited-token.ts

@@ -1,12 +1,13 @@
 import Token from './token'
+import { last } from 'src/util/underscore'
 
 export default class DelimitedToken extends Token {
   trimLeft: boolean
   trimRight: boolean
-  constructor (raw, value, pos, input, file, line) {
-    super(raw, pos, input, file, line)
+  constructor (raw: string, value: string, input: string, line: number, pos: number, file?: string) {
+    super(raw, input, line, pos, file)
     this.trimLeft = value[0] === '-'
-    this.trimRight = value[value.length - 1] === '-'
+    this.trimRight = last(value) === '-'
     this.value = value
       .slice(
         this.trimLeft ? 1 : 0,