code: def get_snapshots(working_dir, start_block=None, end_block=None):
      
  
      # make this usable even if we haven't explicitly configured virtualchain 
      impl = sys.modules[__name__]
      return BlockstackDB.get_consensus_hashes(impl, working_dir, start_block_height=start_block, end_block_height=end_block)
docs: Read the virtualchain snapshots
      Returns the dict of {snapshots: {$block_height: $consensus_hash}} on success
      Returns None on error