package Import;
use Exporter;
@ISA = qw(Exporter);
@EXPORT = qw(load_file);
@EXPORT_OK = qw(_detect_type
                _open_zipped
                _open_unzipped
               );
%EXPORT_TAGS = {STD  => \@EXPORT,
                TEST => \@EXPORT_OK
               };

sub load_file {
  my $filename = shift;
  my $openner = _detect_type($filename);
  &$openner($filename);
  while (my $line = <HANDLE>) {
    ... # do stuff with lines
  }
}

sub _detect_type   {...}
sub _open_zipped   {...}
sub _open_unzipped {...}
1;