croak "Month '$month' out of range 0..11"   if $month > 11 || $month < 0;
    croak "Day '$_[3]' out of range 1..31"      if $_[3] > 31 || $_[3] < 1;
    croak "Hour '$_[2]' out of range 0..23"     if $_[2] > 23 || $_[2] < 0;
    croak "Minute '$_[1]' out of range 0..59"   if $_[1] > 59 || $_[1] < 0;
    croak "Second '$_[0]' out of range 0..59"   if $_[0] > 59 || $_[0] < 0;