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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def pwm_scan_to_gff(self, fa, gfffile, cutoff=0.9, nreport=50, scan_rc=True, append=False):
 """Scan sequences with this motif and save to a GFF file. Scan sequences from a FASTA object with this motif. Less efficient than using a Scanner object. By setting the cutoff to 0.0 and nreport to 1, the best match for every sequence will be returned. The output is save to a file in GFF format. Parameters fa : Fasta object Fasta object to scan. gfffile : str Filename of GFF output file. cutoff : float , optional Cutoff to use for motif scanning. This cutoff is not specifically optimized and the strictness will vary a lot with motif lengh. nreport : int , optional Maximum number of matches to report. scan_rc : bool , optional Scan the reverse complement. True by default. append : bool , optional Append to GFF file instead of overwriting it. False by default. """

        if append:
            out = open(gfffile, "a")
        else:    
            out = open(gfffile, "w")

        c = self.pwm_min_score() + (self.pwm_max_score() - self.pwm_min_score()) * cutoff        
        pwm = self.pwm

        strandmap = {-1:"-","-1":"-","-":"-","1":"+",1:"+","+":"+"}
        gff_line = ("{}\tpfmscan\tmisc_feature\t{}\t{}\t{:.3f}\t{}\t.\t"
                    "motif_name \"{}\" ; motif_instance \"{}\"\n")
        for name, seq in fa.items():
            result = pfmscan(seq.upper(), pwm, c, nreport, scan_rc)
            for score, pos, strand in result:
                out.write(gff_line.format( 
                    name, 
                    pos, 
                    pos + len(pwm), 
                    score, 
                    strandmap[strand], 
                    self.id, 
                    seq[pos:pos + len(pwm)]
                    ))
        out.close()