The dependencies of a source code can only point inwards.

▪ Code dependencies can only move from the outer levels inward .

▪ Code on the inner layers can have no knowledge of

functions on the outer layers.

▪ Inner layer cannot have any information about elements of

an outer layer.

▪ Classes, functions, variables, data format, or any entity

declared in an outer layer must not be mentioned by the

code of an inner layer.

https://betterprogramming.pub/the-clean-architecture-beginners-guide-e4b7058c1165