<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:

def add(one, two=4, three=False):
    ''' This function adds two number.

    :param one: first number to add
    :param two: second number to add
    :rtype: int
    '''
    s = str(int(one) + int(two))

    logging.debug('logging sum from hello.py:' + s)
    print 'printing sum from hello.py:', s

    return s