#                  | inner assignment with a LHS (l) and RHS (r)
#      llllllllll..v...rrrrrrr                                       #
+ $x = 1,   $y = 2,   $z = 3.
  (my ($x, $y, $z) = ( 1, 2, 3 )) = ('a', 'b', 'c' ); 
#      llllllllll.................^..rrrrrrrrrrrrr                   #
+ $x = 'a', $y = 'b', $z = 'c'.
#                                 | outter assignment with a LHS (l) a
+nd RHS (r)
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Slightly changed the internal scalar semantics by eliminating qw.