old_contents: try:
      from Bio import SeqIO
      from Bio.Alphabet import IUPAC
  except ImportError as e:
      print('ERROR: {}'.format(e.msg))
      exit(1)
  
  def load_file(filename, file_format="fasta"):
      """
      Load sequence from file in FASTA file_format
      filename - Path and filename of input sequence file
      """
      content = None
      try:
          content = SeqIO.read(filename, file_format, IUPAC.unambiguous_dna)
      except ValueError as e:
          print('ERROR: {}'.format(e))
          try:
              content = SeqIO.read(filename, file_format, IUPAC.unambiguous_rna)
          except ValueError as e:
              print('ERROR: {}'.format(e))
              exit(1)
  
      if content:
          seq = content.seq
          return seq
      else:
          return None
  
new_contents: try:
      from Bio import SeqIO
      from Bio.Alphabet import IUPAC
  except ImportError as e:
      print('ERROR: {}'.format(e.msg))
      exit(1)
  
  def load_file(filename, file_format="fasta"):
      """
      Load sequence from file and returns sequence as Bio.Seq object
      filename    - String; Path and filename of input sequence file
      file_format - String; Format to be used. Refer to Biopython docs for available formats. Defaults to 'fasta'
      """
      content = None
      try:
          # assume sequence is DNA
          content = SeqIO.read(filename, file_format, IUPAC.unambiguous_dna)
      except ValueError as e:
          # if this fails, try RNA instead
          print('ERROR: {}'.format(e))
          try:
              content = SeqIO.read(filename, file_format, IUPAC.unambiguous_rna)
          except ValueError as e:
              # if this fails, too, raise exception and exit with error code 1
              print('ERROR: {}'.format(e))
              exit(1)
  
      # if some kind of data could be read, return the sequence object
      if content:
          seq = content.seq
          return seq
      # else return None
      else:
          return None
  
subject: Prepare for tagging release 0.1: Add comments to LibCharm.IO