src/plugins/aggregation.js
function (property, callback) {
        this.sum(property, function (sum) {
            this.count(property, function (count) {
                this.fn('avg', callback).call(this, sum/count)
            })
        })
    }
function (property, callback) {
        this.sum(property, function (sum) {
            this.count(property, function (count) {
                this.fn('avg', callback).call(this, sum/count)
            })
        })
    }
function ( property , callback ) { this . sum ( property , function ( sum ) { this . count ( property , function ( count ) { this . fn ( 'avg' , callback ) . call ( this , sum / count ) } ) } ) }
averages a property
averages a property