def search_key(usb_dict, ids):
    """
    Compare provided IDs to the built USB dictionary. If found,
	it will return the common name, otherwise returns the string
	"unknown".
    """
    vendor_key = ids[0]
    product_key = ids[1]

    vendor, vendor_data = usb_dict.get(vendor_key, ['unknown', {}])
    product = 'unknown'
    if vendor != 'unknown':
        product = vendor_data.get(product_key, 'unknown')

    return vendor, product