old_contents: from ..db import get_db
  from ..sequence import get_chrominfo
  
  
  def chromosomes(genome_id):
      """Fetch fasta file name for this genome
          open file with pyfaidx
          get list of chromosomes and fetch their 'chrom_id': len
          retun [{'chrom_id': lenght},]
      """
      db = get_db
      query = """SELECT filename
                 FROM metadata
                 WHERE genome=? AND datatype=sequence"""
      cursor = db.cursor()
      cursor.execute(query, (genome_id, ))
      filename = cursor.fetchone()['filename']
      chrominfo = get_chrominfo(filename)
      return chrominfo
  
new_contents: from ..db import get_db
  from ..sequence import get_chrominfo
  
  
  def chromosomes(genome_id):
      """Fetch fasta file name for this genome
          open file with pyfaidx
          get list of chromosomes and fetch their 'chrom_id': len
          retun [{'chrom_id': lenght},]
      """
      db = get_db()
      query = """SELECT filename
                 FROM metadata
                 WHERE genome=? AND datatype='sequence'"""
      cursor = db.cursor()
      cursor.execute(query, (genome_id, ))
      filename = cursor.fetchone()[0]
      chrominfo = get_chrominfo(filename)
      return chrominfo
  
subject: Implement chromosomes function in genomes