lib/rules/no-unused-vars.js
function inspectVariableDeclarator(emitted) {
            let node = emitted.node;

            if (!emitted.exit) {
                allVariableDeclarations [node.id.name] = node;
            }
        }
function inspectVariableDeclarator(emitted) {
            let node = emitted.node;

            if (!emitted.exit) {
                allVariableDeclarations [node.id.name] = node;
            }
        }
collect all variable declarations from VariableDeclarators and DeclarativeExpressions