my %sequences = (
	"SequenceID|1234_Gene1"  => 'CTTTTAAGCTGATTAGGCTTTTATACCATTAGATTTAGTAACTATTGTCTTTTAA',
	"SequenceID|9876_Gene2"  => 'GTGCTGTCTTAAGTTGAACAGAGTGTGGGAGGAAATATAAGCAAAGTTATTCCGTAGAATT',
	"SequenceID|4567_Gene3" => 'CATCCTCCTTTACACCCCACAAACATTTGGCAACCCCTGATAGGTTTCTTTCTTGTGGA', 
	
);

foreach my $key (keys %sequences)
{
  my $len = length ($sequences{$key});
  print "$key:$len\n";
}