# example structure
my $struct = {
    fruit   => [qw( apple pear )],
    type    => [qw( organic farmed )],
    period  => {
      20050824 => {
        to  => 'new york',
        to  => 'london',
      },
      20050825 => {
        to  => 'auckland',
      },
    }
  };