Parameters
- node: TypedObject | PortableTextBlock<PortableTextMarkDefinition, PortableTextSpan | ArbitraryTypedObject, string, string>
Returns node is PortableTextBlock<PortableTextMarkDefinition, PortableTextSpan | ArbitraryTypedObject, string, string>
True if valid Portable Text block, otherwise false
Strict check to determine if node is a correctly formatted Portable Text block.