Create GFF3 feature exporter. The information is below:
Your answer looks like a good start. You'll probably want to use sys.argv, argparse, or another argument parsing tool to read in options from the command line, then compare them to the fields (e.g. the &quot;type&quot; argument gets compared with the type column).
Given that attributes can be arranged in an arbitrary order, you'll probably need to read all of them from each line and store in a dict in order to determine whether the target is present. A regular expression search is another way to do that.
There are a few libraries available (e.g. from biopython) for reading and subsetting FASTA records.