docs: def write_sequences(path, seqs):
      """
      Write the given sequence to the given path, using the file format implied 
      by the path's file extension.
  
      Arguments
      =========
      path: str or pathlib.Path
          The name of the file to create.  Allowed extensions are:
          
          - *.fa, *.fas, *.fasta
          - *.tsv, *.csv
          - *.xlsx
  
      seqs: dict
          A mapping of names to sequences, which can be either protein or DNA.
      """
      path = Path(path)
  
      if path.suffix in ('.fa', '.fas', '.fasta'):
          write_sequences_to_fasta(path, seqs)
  
      elif path.suffix in ('.tsv', '.csv'):
          write_sequences_to_tsv(path, seqs)
  
      elif path.suffix in ('.xlsx',):
          write_sequences_to_xlsx(path, seqs)
  
      else:
          raise scripting.UserError("""\
  '{}' has unknown output filetype '{}'.  Please provide a path with one of the 
  following extensions:
  
  - *.fa, *.fas, *.fasta
  - *.tsv, *.csv
  - *.xlsx
  """.format(path, path.suffix))