function isInsideOfStorableFunction(id, rhsNode) {
			const funcNode = astUtils.getUpperFunction(id);

			return (
				funcNode &&
				isInside(funcNode, rhsNode) &&
				isStorableFunction(funcNode, rhsNode)
			);
		}
Checks whether a given Identifier node exists inside of a function node which can be used later.

"can be used later" means:
- the function is assigned to a variable.
- the function is bound to a property and the object can be used later.
- the function is bound as an argument of a function call.

If a reference exists in a function which can be used later, the reference is read when the function is called.
@param {ASTNode} id An Identifier node to check.
@param {ASTNode} rhsNode The RHS node of the previous assignment.
@returns {boolean} `true` if the `id` node exists inside of a function node which can be used later.
@private