move Python & Raku code apart, state the language for each

Author: schultzdavid

doc/Language/py-nutshell.rakudoc

@@ -405,16 +405,21 @@ I<Raku>
 Declaring a function (subroutine) with C<def> in Python is accomplished
 with C<sub> in Raku.
 
+Python
+
 =begin code :lang<python>
-def add(a, b):       # Python
+def add(a, b):
     return a + b
+=end code
+
+Raku
 
-sub add(\a, \b) {    # Raku
+=begin code
+sub add(\a, \b) {
     return a + b
 }
 =end code
 
-
 The C<return> is optional; the value of the last expression is used as
 the return value: