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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 get_recid_from_ref(ref_obj):
 """Retrieve recid from jsonref reference object. If no recid can be parsed, returns None. """

    if not isinstance(ref_obj, dict):
        return None
    url = ref_obj.get('$ref', '')
    return maybe_int(url.split('/')[-1])