Update src/poly_a.py

src/poly_a.py

@@ -70,23 +70,32 @@ def generate_poly_a(
     tail_bases: List[str] = choices(bases, weights=norm_weights, k=length)
     return "".join(tail_bases)
 
+
 def main():
+    """Append poly A tails to fasta sequences and write to file
+    
+    This function iterates over `input` fasta sequences from a specified file, 
+    appends tails of given `length` and composition specified by `weights`, 
+    and writes them to file specified as `output`.
+    """
+
     parser = argparse.ArgumentParser(description='Process some integers.')
     parser.add_argument('-i', '--input', required=True,
-                    help='Fasta file to add tails to')
+                        help='Fasta file to add tails to')
     parser.add_argument('-o', '--output', default="out.fa",
-                    help='Name of the output Fasta file (default = out.fa)')
+                        help='Name of the output Fasta file (default = out.fa)')
     parser.add_argument('--length', default=100, type=int,
-                    help='Length of the desired tail (max value = 200)')
+                        help='Length of the desired tail (max value = 200)')
     parser.add_argument('--weights', default=(0.914, 0.028, 0.025, 0.033), type=float, nargs='+',
-                    help="Tuple of relative A, C, G and U frequencies in the tail")
+                        help="Tuple of relative A, C, G and U frequencies in the tail")
     args = parser.parse_args()
 
-    new_records = []    
+    new_records = []
     for fasta in SeqIO.parse(open(args.input),'fasta'):
         new_seq = fasta.seq + Seq(generate_poly_a(args.length, args.weights))
         new_records.append(SeqRecord(new_seq, id=fasta.id, description=fasta.description))
     SeqIO.write(new_records, args.output, "fasta")
 
+
 if __name__ == '__main__':
     main()