[refactoring] removed star imports, renamed cst in U

and applied flake8 guidelines

run_selector.py

@@ -5,10 +5,12 @@
 import glob
 import os
 from functools import partial
+import numpy as np
 
+import yaml
 import f90nml
 
-from pp_params import *
+from pp_params import default_params
 
 
 class NamelistRecursive:
@@ -247,7 +249,7 @@ class RunSelector:
         runs = self.nml_select(runs, filter_nml)
 
         # Sort by the value in the namelist of sort_run_by
-        if not sort_run_by is None:
+        if sort_run_by is not None:
             if type(sort_run_by) == str:
                 sort_run_by = [sort_run_by]
             for nml_key in reversed(sort_run_by):