Even Numbers |2|
~~~~~~~~~~~~~~~~

Write a recursive function named *is_even* that determines whether a
given integer is even or not. The function takes one integer value as
input which is greater than or equal to zero and returns ``True`` if the
given number is even or returns ``False`` if the given number is odd.

**You cannot use modulo operator (``%``).**

*Hint:* You should think what are the base conditions for the function.

.. container:: sampleio

   Sample I/O:

.. |2| image:: ../../figures/difficulty_four.png
   :class: difficulty

.. code:: default

   >>> is_even(122)
   True


   >>> is_even(55)
   False


   >>> is_even(1)
   False


   >>> is_even(0)
   True

.. raw:: html

   <button type="button" class="collapsible" onclick="toggle()">

Show the Answer

.. raw:: html

   </button>

.. raw:: html

   <div class="hiddenanswer">

.. code:: python

   def is_even(number):
       if(number == 1):
           return False
       elif(number == 0):
           return True
       else:
           return is_even(number-2)

.. raw:: html

   </div>