use vars qw/$x, @y, %z, $d, @e, %f, $p, @q, %r/;
 $a = 10;
 my ($b) ; # what is the meaning of bracket around variable name ?

{
  # ...
  my ($p, @q, %r); 
  local ($d, @e, %f);      # (1)
  # ...
  sub foo { # ...
  }
  # ...
  foo(17);               # (2)
  bar($p,29);            # (3)
  lbar($d, 31);
  # ...
}                        # (4)
# ...
sub bar { # ...
}

{
  # ...
  local ($x, @y, %z);     # (5)
  local $a = 20;
  my $a = 30;
  # ...
  sub baz { # ...
  }
  # ...
  baz(17);                # (6)
  quux($x,29);            # (7)
  # ...
  sub child {
  
  $b = a * 10; # which value of \$a will be available here ?
  
 }
}                         # (8)
# ...
sub quux { # ...
}
# ...
baz(29);                  # (9)