Variables defined within a function block are not variables which can be accessed from outside the function block. The function block is said to have it’s own local scope, also referred to as a namespace (or, the space where a given variable name is assigned), and that block scope is separate from the top-level global scope of the interpreter.

Nested Scopes

The block scopes can be nested. A nested scope is a scope that is defined within another scope. Any scope which is nested can read variables from scopes which enclose the nested scope.