$a = 10;
 my $b = 20; # Can this be accessed inside the subroutine ?
 my ($c) = 30; # what is the meaning of bracket around variable name ?

{
  # ...
  my ($p, @q, %r); 
  local ($d, @e, %f);      # (1)
  $b = 40; # does this change value of my $b ?
  # ...
  sub foo { # ...
  }
  # ...
  foo(17);               # (2)
  bar($p,29);            # (3)
  lbar($d, 31);
  # ...
}                        # (4)
# ...
sub bar { 
my $d = 60;
$b = 50; # ...
}