Prolog queries that return false after true (Enter vs Spacebar)

This video explains why sometimes you see a "false" answer for a query that also returns true.

TL;DR - use "Enter" when you get a query result you are happy with

0:05 - The example rule we will use
0:24 - Side note: don't use "is" (or anything else) to check for equality - just use the value!
0:43 - Consulting the file
0:49 - Responding to a query result with Enter
1:18 - Responding to a query result with Spacebar
1:32 - Why this happens