[Area] Interfaces Suppose an interface had a method that input a parameter of an int. In a class that implements the interface, it was possible to write the method with a parameter of a str. Now the parameter signatures of the method must exactly match between the interface and the implementation of the method on a class. Also, the return types must match exactly. For more information, see Interfaces Overview. [Syntax rule] 
Implementation of an interface method must match the parameter signature exactly