Easiest way

from operator import itemgetter
from itertools import groupby
import fitz
doc = fitz.open( 'mydocument.pdf' )
for page in doc:
 text_words = page.get_text_words()
 # The words should be ordered by y1 and x0
 sorted_words = SortedCollection( key = itemgetter( 3, 0 ) )
 for word in text_words:
 sorted_words.insert( word )
 # At this point you already have an ordered list. If you need to 
 # group the content by lines, use groupby with y1 as a key
 lines = groupby( sorted_words, key = itemgetter( 3 ) )
 # Enjoy!