new_contents: '''
      Tests
  '''
  import pytest
  
  def test_init(smpl_fasta):
      assert len(smpl_fasta['chr1']) == 500000
      assert len(smpl_fasta['chr2']) == 500000
      assert len(smpl_fasta['chr3']) == 500000
      assert len(smpl_fasta['chr4']) == 500000
  
subject: add fasta tests