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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 EventIvorn(ivorn, cite_type):
 """ Used to cite earlier VOEvents. Use in conjunction with :func:`.add_citations` Args: ivorn(str):
 It is assumed this will be copied verbatim from elsewhere, and so these should have any prefix (e.g. 'ivo://','http://') already in place - the function will not alter the value. cite_type (:class:`.definitions.cite_types`):
 String conforming to one of the standard citation types. """

    # This is an ugly hack around the limitations of the  lxml.objectify API:
    c = objectify.StringElement(cite=cite_type)
    c._setText(ivorn)
    c.tag = "EventIVORN"
    return c