Scala - type bounds notation for beginners

For beginners in Scala (like me) type bounds notation causes difficulty. I tried to write  short cheat sheet with Scala type bounds notation:

Scala notation	Meaning	Remarks
[+T]	Only subclass may be used	Covariant
[-T]	Only superclass may be used	Contravariant
[T]	Only specified type may be used	Invariant
[X <: B]	Declares that type variable X refers to a subtype of type B	Upper type bounds
[X >: B]	Declares that type variable X refers to a supertype of type B	Lower type bounds

Remarks:

• Supertype - parent type
• Subtype - child type

See code examples on Git