docs: def compare_registries(fs0, fs1, concurrent=False):
      """Compares the Windows Registry contained within the two File Systems.
  
      If the concurrent flag is True,
      two processes will be used speeding up the comparison on multiple CPUs.
  
      Returns a dictionary.
  
          {'created_keys': {'\\Reg\\Key': (('Key', 'Type', 'Value'), ...)}
           'deleted_keys': ['\\Reg\\Key', ...],
           'created_values': {'\\Reg\\Key': (('Key', 'Type', 'NewValue'), ...)},
           'deleted_values': {'\\Reg\\Key': (('Key', 'Type', 'OldValue'), ...)},
           'modified_values': {'\\Reg\\Key': (('Key', 'Type', 'NewValue'), ...)}}
  
      """
      hives = compare_hives(fs0, fs1)
  
      if concurrent:
          future0 = concurrent_parse_registries(fs0, hives)
          future1 = concurrent_parse_registries(fs1, hives)
  
          registry0 = future0.result()
          registry1 = future1.result()
      else:
          registry0 = parse_registries(fs0, hives)
          registry1 = parse_registries(fs1, hives)
  
      return registry_comparison(registry0, registry1)