def get_strains(output_file):
  """
    Returns a dictionary that maps cell id to strain.
    Takes Biocellion output as the input file.
  """
  strain_map = {}
  with open(output_file, 'r') as f:
    for line in f:
      if line.startswith("Cell:"):
        tokens = line.split(',')
        cell = int(tokens[0].split(':')[1])
        strain = int(tokens[1].split(':')[1])
        strain_map[cell] = strain
  return strain_map