dd docstring for explain for Explicable

pymath/calculus/explicable.py

@@ -20,10 +20,20 @@ class Explicable(Renderable):
         self.steps = []
 
     def explain(self, noself=True):
-        """ Generate and render steps  which leed to itself
+        r""" Generate and render steps  which leed to itself
 
         :param noself: does explain return self
 
+        >>> action = Explicable()
+        >>> from .expression import Expression
+        >>> action.postfix_tokens = Expression('42')
+        >>> action.this_append_before([Expression('2+10*4'), Expression('2+40')])
+        >>> for i in action.explain():
+        ...    print(i)
+        2 + 10 \times 4
+        2 + 40
+        42
+        
         """
         old_s = ''
         # les étapes pour l'atteindre