<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def get_attributes(user, service):
 """ Return a dictionary of user attributes from the set of configured callback functions. """

    attributes = {}
    for path in get_callbacks(service):
        callback = import_string(path)
        attributes.update(callback(user, service))
    return attributes