Returns a null value for each of various kinds of test values.

    **Parameters**

            **test** :  bool, int, float or string

                    Value to test.


    **Returns**
            **null** :  element in `[False, 0, 0.0, '']`

                    Null value corresponding to the given test value:

                    *   if `test` is a `bool`, return `False`
                    *   else if `test` is an `int`, return `0`
                    *   else if `test` is a `float`, return `0.0`
                    *   else `test` is a `str`, return `''`

def DEFAULT_NULLVALUE(test):
    """
    Returns a null value for each of various kinds of test values.

    **Parameters**

            **test** :  bool, int, float or string

                    Value to test.


    **Returns**
            **null** :  element in `[False, 0, 0.0, '']`

                    Null value corresponding to the given test value:

                    *   if `test` is a `bool`, return `False`
                    *   else if `test` is an `int`, return `0`
                    *   else if `test` is a `float`, return `0.0`
                    *   else `test` is a `str`, return `''`

    """
    return False if isinstance(test,bool) \
           else 0 if isinstance(test,int) \
           else 0.0 if isinstance(test,float) \
           else ''