Function isPortableTextBlock

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