bpo-26205: Specify the number of nested scopes (GH-21324) (GH-21342)

* Clarify number of scopes

* Indicate 3 or 4

Co-authored-by: Terry Jan Reedy <tjreedy@udel.edu>

Co-authored-by: Terry Jan Reedy <tjreedy@udel.edu>
(cherry picked from commit 9ed3cd8)

Co-authored-by: Joannah Nanjekye <33177550+nanjekyejoannah@users.noreply.github.com>

Co-authored-by: Joannah Nanjekye <33177550+nanjekyejoannah@users.noreply.github.com>

Author: miss-islington

Doc/tutorial/classes.rst

@@ -114,8 +114,8 @@ accessible.  "Directly accessible" here means that an unqualified reference to a
 name attempts to find the name in the namespace.
 
 Although scopes are determined statically, they are used dynamically. At any
-time during execution, there are at least three nested scopes whose namespaces
-are directly accessible:
+time during execution, At any time during execution, there are 3 or 4 nested
+scopes whose namespaces are directly accessible:
 
 * the innermost scope, which is searched first, contains the local names
 * the scopes of any enclosing functions, which are searched starting with the