sub calcWeight {
  my($item)   = @_;
  my($weight) = 0;
  my($part);

  $numParts = scalar(@parts = getParts($item));

  if ( $numParts == 0 ) {
    return(getWeight($item));
  }
  elsif ( $numParts == 1 ) {
    return(getWeight($parts[0]));
  }
  else {
    for $part ( @parts ) {
      $weight += calcWeight($part);
    }
  }

  return($weight);
}