new_contents: """
  Reformat a single entry fasta file.
  
  E.g. useful if a fasta file contains a sequence in a single long
  line. The Biopython SeqIO writer will generate a sequence with 
  proper line lenght of 60 character.s
  
  """
  
  import argparse
  from Bio import SeqIO
  
  parser = argparse.ArgumentParser()
  parser.add_argument("input_fasta")
  parser.add_argument("output_fasta")
  args = parser.parse_args()
  SeqIO.write(SeqIO.read(args.input_fasta, "fasta"), args.output_fasta, "fasta")
  
subject: Add fasta line break script