get_unshift_code(): better algo; no more used by unflatten

cadbiom/models/clause_constraints/mcl/MCLSolutions.py

@@ -77,15 +77,11 @@ class RawSolution(object):
         @param var_num: DIMACS literal coding of a shifted variable x_i
         @return: DIMACS literal coding of  x_0 with same value
         """
-        if var_num < 0: 
-            varnum1 = -var_num
-            sign = -1
-        else: 
-            varnum1 = var_num
-            sign = 1
-        var_code = (varnum1 - 1) % self.__shift_step + 1
+
+        var_code = (abs(var_num) - 1) % self.__shift_step + 1
+
         if var_code <= self.__shift_step:
-            return var_code*sign
+            return var_code * (-1 if var_num < 0 else 1)
         else:
             raise MCLException("Not a DIMACS code of an initial variable")