how to determine the block is a freetext_annot or others?

[AwesomeYuer]

sortBlocks = True
for i, block in enumerate(page.get_text("blocks", sort=sortBlocks)):
   # by using below? or ...?
   page.get_text("dict", sort=sortBlocks)["blocks"][i]
   block[5] 

I found nothing about below and above in online document and old discussions.

• block[5] block_no starts with what? from 1 or 0?
• block[6] block_type What is the value's range and meaning of it?

Thanks in advance?