Define a Scalar

# Macro attributes

| Attribute        | description                                                                                                                                                            | Type   | Optional |
|------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------|----------|
| name             | Scalar name                                                                                                                                                            | string | Y        |
| specified_by_url | Provide a specification URL for this scalar type, it must link to a human-readable specification of the data format, serialization and coercion rules for this scalar. | string | Y        |