message: util.isNumber is deprecated
diff: import * as vscode from 'vscode'
  import * as fs from 'fs'
  -import { isNumber } from 'util'
  export class TextDocumentLike {
  private readonly _lines: string[]
  @@ -85,7 +84,7 @@ export class TextDocumentLike {
  lineAt(lineNum: number): TextLineLike
  lineAt(position: vscode.Position): TextLineLike
  lineAt(lineNum: number | vscode.Position) {
  - if (isNumber(lineNum)) {
  + if (typeof lineNum === 'number') {
  return new TextLineLike(this._lines[lineNum])
  } else {
  return new TextLineLike(this._lines[lineNum.line])
  