- [Nodes](https://github.com/kdl-org/kdl/blob/main/SPEC.md#node) can be defined as elements of the root JSON array (`[]`)
- Each node must have the `identifier` field of type [Identifier](https://github.com/kdl-org/kdl/blob/main/SPEC.md#identifier) and can have these optional fields:
-`arguments` (Array of [Values](https://github.com/kdl-org/kdl/blob/main/SPEC.md#value))
-`properties` (Object with [Identifier](https://github.com/kdl-org/kdl/blob/main/SPEC.md#identifier):[Value](https://github.com/kdl-org/kdl/blob/main/SPEC.md#value) pairs)