add new setting for no_repetition decorator

pymath/calculus/decorators.py

@@ -3,10 +3,11 @@
 
 from functools import wraps
 
-def no_repetition(equals=lambda x,y: x == y):
+def no_repetition(equals=lambda x,y: x == y, old = ""):
     """ Remove yield values which has already been yield
 
-    :param fun: a generator
+    :param equals: test for equality
+    :param old: initiate form of data.
     :returns: same generator with no repetitions
 
     >>> norep = no_repetition()
@@ -22,7 +23,7 @@ def no_repetition(equals=lambda x,y: x == y):
         @wraps(fun)
         def dont_repeat(*args, **kwrds):
             gen = fun(*args, **kwrds)
-            old_s = ""
+            old_s = old
             while True:
                 try:
                     new_s = next(gen)