Function isPortableTextToolkitSpan

isPortableTextToolkitSpan(
    span:
        | TypedObject
        | ToolkitNestedPortableTextSpan<PortableTextMarkDefinition>,
): span is ToolkitNestedPortableTextSpan<PortableTextMarkDefinition>
Loose check to determine if span is a toolkit span node. Only checks _type, assumes correct structure.
Parameters
- span: TypedObject | ToolkitNestedPortableTextSpan<PortableTextMarkDefinition>
  Span to check
Returns span is ToolkitNestedPortableTextSpan<PortableTextMarkDefinition>
True if toolkit span, otherwise false