While using a OOP language.

    Welcome to Node.js v24.10.0.
    Type ".help" for more information.
    > const fn = (x) => x + x
    undefined
    > typeof(fn)
    'function'
    > Object.getOwnPropertyNames(fn)
    [ 'length', 'name' ]
    > fn.name
    'fn'
    > fn.length
    1
    > Object.getPrototypeOf(fn)
    [Function (anonymous)] Object