sort optimization

	} @{ $self->{results} };

	@{ $self->{results} }

	  = sort { $a->{datetime} <=> $b->{datetime} } @{ $self->{results} };

	  = sort { $a->{epoch} <=> $b->{epoch} } @{ $self->{results} };

	# wings (different departures which are coupled as one train) contain

	# references to each other. therefore, they must be processed last.

	$ref->{date}  = $dt->strftime('%d.%m.%Y');

	$ref->{time}  = $dt->strftime('%H:%M');

	$ref->{epoch} = $dt->epoch;

	$ref->{route_pre} = $ref->{sched_route_pre}

	  = [ split( qr{[|]}, $ref->{route_pre} // q{} ) ];

	# departure is preferred over arrival, so overwrite default values

	$self->{date}     = $result->{date};

	$self->{time}     = $result->{time};

	$self->{epoch}    = $result->{epoch};

	$self->{datetime} = $result->{datetime};

	$self->{train_id} = $result->{train_id};

	$self->{train_no} = $result->{train_no};