//float quantity for get rate,
//isInverse bool, this product is a inverse of standard pair (get from ds_products.is_inverse)
//spreads array, set of spreads objects (get from ds_products.Spread)
//return rate float, bid rate of quantity
function getBidRate(qty, isInverse, spreads) {
	var quoteType = ( isInverse ? 'inv_' : '' ) + 'bid';
	var buckets = (_.sortBy(spreads, function(o) { return o.min; })).reverse();
	var priceObj = _.find(buckets, function(price) {
		if(price.deleted_at) return false;
		return (price.min && qty >= price.min);
	});
	if (priceObj === undefined) { // if not match any range use default
		priceObj = _.find(buckets, function(price) {
			return price.is_default;
		});
	}
	var rate = priceObj[quoteType];
	return rate;
}