Rewrite __m_shift_clause with comprehension list

cadbiom/models/clause_constraints/mcl/CLUnfolder.py

@@ -460,16 +460,9 @@ class CLUnfolder(object):
         @warning: lock the unfolder
         """
         self.__locked = True  # shift_step must be frozen
-        shift_c = []
-        for lit in ncl:
-            if lit > 0:
-                slit = lit + self.__shift_step * nb_steps
-            else:
-                slit = lit - self.__shift_step * nb_steps
-            shift_c.append(slit)
-        return shift_c
-
 
+        return [(lit + self.__shift_step * nb_steps) if lit > 0
+                else (lit - self.__shift_step * nb_steps) for lit in ncl]
 
     def __shift_dynamic(self):
         """