code: function VariableDeclarator(path) {
        var id = path.get("id");
        if (!id.isIdentifier()) return;
  
        var init = path.get("init");
        if (!isValidRequireCall(init)) return;
  
        var source = init.node.arguments[0];
        this.sourceNames[source.value] = true;
        this.sources.push([id.node, source]);
  
        path.remove();
      }
docs: /*istanbul ignore next