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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_suitable_slot_for_reference(self, reference):
 """Returns the suitable position for reference analyses, taking into account if there is a WorksheetTemplate assigned to this worksheet. By default, returns a new slot at the end of the worksheet unless there is a slot defined for a reference of the same type (blank or control) in the worksheet template's layout that hasn't been used yet. :param reference: ReferenceSample the analyses will be created from :return: suitable slot position for reference analyses """

        if not IReferenceSample.providedBy(reference):
            return -1

        occupied = self.get_slot_positions(type='all') or [0]
        wst = self.getWorksheetTemplate()
        if not wst:
            # No worksheet template assigned, add a new slot at the end of the
            # worksheet with the reference analyses there
            slot_to = max(occupied) + 1
            return slot_to

        # If there is a match with the layout defined in the Worksheet Template,
        # use that slot instead of adding a new one at the end of the worksheet
        slot_type = reference.getBlank() and 'b' or 'c'
        layout = wst.getLayout()

        for pos in layout:
            if pos['type'] != slot_type:
                continue
            slot_to = int(pos['pos'])
            if slot_to in occupied:
                # Not an empty slot
                continue

            # This slot is empty, use it instead of adding a new slot at the end
            # of the worksheet
            return slot_to

        # Add a new slot at the end of the worksheet, but take into account
        # that a worksheet template is assigned, so we need to take care to
        # not override slots defined by its layout
        occupied.append(len(layout))
        slot_to = max(occupied) + 1
        return slot_to