Finding the most common 7-mer in a FASTA file

Your task

Write a script to print out the most common 7-mer and its GC percentage from all the sequences in data/records.fa. You are free to reuse your existing toolbox.

• The example FASTA file was adapted from: Genome Biology DNA60 Bioinformatics Challenge.

Hints

• FASTA files have two types of lines: header lines starting with a ">" character and sequence lines. We are only concerned with the sequence line.
• Read the string functions documentation.
• Read the documentation for built in functions.
• Parse command line arguments

Challenges

• Find out how to change your script so that it can read from data/challenge.fa.gz without unzipping the file first (hint: check standard library).
• Can you add a command line argument parser such that you are able to specify the path towards the input file from the command line?
• Can you change the parser so that there is an option flag to tell the program whether the input file is gzipped or not?
• Can you change your script so that it works for any N-mers instead of for just 7-mers?