The DNA sequences could be spread over multiple lines; however, the OP sample data only showed single lines. My code dealt with the sample data that was presented.

Records could start with a semicolon. The OP sample data did not show any such records, so I made no attempt to process that either.

There could be errors in the input — for instance, illegally embedded blank lines or letters that didn't represent a nucleotide — which I made no attempt to validate.

I made it clear that the solution I presented was "code something like this". It provides the basic elements of what is required based on what was asked. If there are additional, or different, requirements which the OP cannot code, that should form a follow-up question.