message: Add exception to prefer-get rule for type guard returns
diff: @@ -22,7 +22,7 @@ class PreferGetWalker extends Lint.RuleWalker {
  public visitMethodDeclaration(node: ts.MethodDeclaration) {
  if (node.parameters.length !== 0)
  return;
  - if (this.isPrivate(node))
  + if (this.isPrivate(node) || this.returnsTypeGuard(node))
  return;
  const name = node.name.getText();
  @@ -42,6 +42,15 @@ class PreferGetWalker extends Lint.RuleWalker {
  return false;
  }
  + private returnsTypeGuard(node: ts.MethodDeclaration): boolean {
  + if (node.type === undefined)
  + return false;
  + const returnText = node.type.getText();
  + if (returnText.slice(0, 8) === "this is ")
  + return true;
  + return false;
  + }
  +
  private hasGetterName(name: string): boolean {
  if ((name.length > 2 && name.slice(0, 2) === "is" && name.charAt(2) === name.charAt(2).toUpperCase()) ||
  (name.length > 3 && name.slice(0, 3) === "has" && name.charAt(3) === name.charAt(3).toUpperCase()) ||
  