@Override
  public boolean isEquivalentTo(@Nullable PsiElement another) {
    return another instanceof GrBindingVariable &&
           StringUtil.equals(getName(), ((GrBindingVariable)another).getName()) &&
           getManager().areElementsEquivalent(getContainingFile(), another.getContainingFile());
  }
@Override
  public boolean isEquivalentTo(@Nullable PsiElement another)