The worth during the parenthesis would be the implicit parameter and the object itself would be the express parameter, methods that don't have express parameters, use implicit parameters, the fillTank method has the two an explicit and an implicit parameter. Allows take a more in-depth look at the fillTank system https://emilioyyuqn.estate-blog.com/28395240/the-smart-trick-of-thisav-that-no-one-is-discussing