Lexical Variables

• Declare "private," "scoped," or "lexical" variables with the my keyword.
• Name your parameters.

sub sum_of_three_numbers {
  my ( $a, $b, $c );
  ( $a, $b, $c ) = @_;
  $a + $b + $c;
}
# outside the sub, we can't get to @_, $a, $b, or $c