Eloquent-like syntax to filter records in Xero API request

[DLO33]

When filtering quotes (and other data), what is the syntax as it does work as per the contacts example?

For example:
$invoices = $xero->invoices()->where('InvoiceNumber', 9871)->get();

Renders the following:
/api.xro/2.0/Invoices?where=InvoiceNumber%3D%3D9871

Ultimately this should be:
/api.xro/2.0/Invoices?InvoiceNumber=9871

[DLO33]

I've been able to get this to work, but it does look like a 'hack'. Is there a better way?

$xero->invoices()->find('?InvoiceNumber=' . $request->get('InvoiceNumber'));

This renders the following url:
/api.xro/2.0/Invoices/?InvoiceNumber=9871