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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def enable_event(library, session, event_type, mechanism, context=None):
 """Enable event occurrences for specified event types and mechanisms in a session. Corresponds to viEnableEvent function of the VISA library. :param library: the visa library wrapped by ctypes. :param session: Unique logical identifier to a session. :param event_type: Logical event identifier. :param mechanism: Specifies event handling mechanisms to be enabled. (Constants.VI_QUEUE, .VI_HNDLR, .VI_SUSPEND_HNDLR) :param context: :return: return value of the library call. :rtype: :class:`pyvisa.constants.StatusCode` """

    if context is None:
        context = constants.VI_NULL
    elif context != constants.VI_NULL:
        warnings.warn('In enable_event, context will be set VI_NULL.')
        context = constants.VI_NULL  # according to spec VPP-4.3, section 3.7.3.1
    return library.viEnableEvent(session, event_type, mechanism, context)