> in proper functional languages data is immutable. Once you have set a variable you can not change it. Immutability != single assignment. Two separate concept

> in proper functional languages data is immutable. Once you have set a variable you can not change it. Immutability != single assignment. Two separate concepts, often confused. Elixir is immutable but allows variable shadowing, in which a new variable with the same name is created and the old variable is tossed.