Update README example to not overwrite function as variable name

README.md

@@ -64,13 +64,13 @@ from supermemo2 import first_review, review
 # first review
 # using quality=4 as an example, read below for what each value from 0 to 5 represents
 # review date would default to datetime.utcnow() (UTC timezone) if not provided
-first_review = first_review(4, "2024-06-22")
-# first_review prints { "easiness": 2.36, "interval": 1, "repetitions": 1, "review_datetime": "2024-06-23 01:06:02"))
+r = first_review(4, "2024-06-22")
+# review prints { "easiness": 2.36, "interval": 1, "repetitions": 1, "review_datetime": "2024-06-23 01:06:02"))
 
 # second review
-second_review = review(4, first_review["easiness"], first_review["interval"], first_review["repetitions"], first_review["review_datetime"])
+second_review = review(4, r["easiness"], r["interval"], r["repetitions"], r["review_datetime"])
 # or just unpack the first review dictionary
-second_review = review(4, **first_review)
+second_review = review(4, **r)
 # second_review prints similar to example above.
 ```