9. Consider the following Python program: Y 3 z-5; def subl ) a7; 211 def sub2 ) global x; a13 x15 w-17 def sub3 ): nonlocal a; a-19 b 21; z23 List all the variables, along with the program units where they are declared, that are visible in the bodies of subl, sub2, and sub3, assum ing static scoping is used