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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 process_form(self, instance, field, form, empty_marker=None, emptyReturnsMarker=False):
 """Return a UID so that ReferenceField understands. """

        fieldName = field.getName()
        if fieldName + "_uid" in form:
            uid = form.get(fieldName + "_uid", '')
            if field.multiValued and\
                    (isinstance(uid, str) or isinstance(uid, unicode)):
                uid = uid.split(",")
        elif fieldName in form:
            uid = form.get(fieldName, '')
            if field.multiValued and\
                    (isinstance(uid, str) or isinstance(uid, unicode)):
                uid = uid.split(",")
        else:
            uid = None
        return uid, {}