Урок - Типы Данных / Data Types

AnyType - can be any value.

Callback - callback function.

Counter - a positive integer that is greater than or equal to zero.

• bad: price - it's real not integer.
• bad: temperature - can be negative.
• be careful: age - can be unknown.
• good: amount of elements - always zero or positive value.

TheSameClass - returns an object of the same class.

This - returns a reference to the current object.