generic_extension.swift

extension Buffer {
    
    var isEmpty: Bool {
        return items.isEmpty
    }
    
    var middle: Element? {
        return try? get(index: items.count / 2)
    }
    
}

var doubleBuffer = Buffer<Double>()
doubleBuffer.add(9.2)
doubleBuffer.add(3.54)
doubleBuffer.add(13.04)

print("middle: \(String(describing: doubleBuffer.middle))")
/*
 middle: Optional(3.54)
 */