@startuml class-diagram.png
skinparam handwritten true
skinparam monochrome true
skinparam packageStyle rect
skinparam defaultFontName FG Virgil
skinparam shadowing false

actor User
participant CalculatorApp
participant Calculator

create Calculator
CalculatorApp -> Calculator : new
Calculator -> Calculator : accumulator=0.0

User --> CalculatorApp : "add 5.5"
CalculatorApp ->> Calculator : doOperation("add", 5.5)
CalculatorApp <<-- Calculator : returns 5.5
User <<-- CalculatorApp : displays "5.5"


@enduml
