code: def chromosomes_from_fai(genome_fai):
      
      chromosomes = []
      with open(genome_fai) as fai_file:
          for line in fai_file:
              line = line.strip().split()
              chromosomes.append(line[0])
      return chromosomes
docs: Read a fasta index (fai) file and parse the input chromosomes.
  
      :param str genome_fai: Path to the fai file.
      :return: list of input chromosomes
      :rtype: list[str]