<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def update(d,ud):
 """ Recursively merge the values of ud into d. """

    if ud is None:
        return
    for key,value in ud.items():
        if not key in d:
            d[key] = value
        elif isinstance(value,dict):
            update(d[key],value)
        else:
            d[key] = value