As titled.
Thanks to this symbol, other libraries that accept validation objects, can directly accept fluent schema objects and call .valueOf internally.
This vastly improves the user experience and hides one of the most common mistakes that devs make with this library.

const S = require('fluent-schema')

const schema = S.object()
  .prop('foo', S.string())
  .prop('bar', S.number())

console.log(schema[Symbol.for('fluent-schema-object')]) // true

Once this pr is merged and released, I'll open a pr to Fastify to support this new feature.