Index property will return entity's index in the
collection of ALL entities - as they are accessible through
wodHtmlParser.Parts
property.
No matter if specific entity is accessed through
wodHtmlParser.Parts property, or through
wodHtmlEntity.Parts
property, index will always be the same - with respect to
main wodHtmlParser's collection. This is understandable
since child Parts collection are containing copies of
entities accessible through main Parts collection.