Where would a component specific helper function go in a project folder structure?

[AnnaYuS]

The question is somewhat related to this discussion
In what folder would you put a ts file with one or two helper functions? The functions are used in only one component, but you've decided to extract them in a separate file so that you could test it easily.
It could go into a separate folder like helpers or utils or lib. What speaks against it is that the files that are usually found in these type of folders have reusable functions, but the function in question is specific to the component and is not going to be reused.
Another option is to put it next to the vue component where it is used like so:

.
├── components
│   └── YourComponent.vue
│   └── specificFunctionForYourComponent.ts

I haven't seen it done in other projects, but it might be a good idea? What do you think?