better way to handle mpi

aggregator.py

@@ -4,16 +4,13 @@ import numpy as np
 from functools import partial
 from baseprocessor import Rule
 import snapshotprocessor
-
+from mypool import MyPool
 
 try:
     from mpi4py.futures import MPIPoolExecutor
-
-    mpi = True
+    mpi_loaded = True
 except ModuleNotFoundError:
-    from mypool import MyPool
-
-    mpi = False
+    mpi_loaded = False
 
 
 def _map_aux(fun, path, path_out, params, run_num, **kwargs):
@@ -57,7 +54,7 @@ class Aggregator:
             map_fn = partial(
                 _map_aux, func, self.path, self.path_out, self.params, **kwargs
             )
-            if mpi:
+            if mpi_loaded and self.params.process.mpi:
                 executor = MPIPoolExecutor(max_workers=num_process)
                 try:
                     result = list(executor.map(map_fn, run_num, unordered=True))