access preceding record

I'm about new to XSLT
and wonder wether this could possible thru transformation:

A sortet set of records - each containing one value -
should be transformed into the same number of records
with two values where the second value is that from the preceding record.

example input is
<base>
<record><start>3</start></record>
<record><start>2</start></record>
<record><start>1</start></record>
</base>

example output should be
<base>
<record><start>3</start><stop></stop></record>
<record><start>2</start><stop>3</stop></record>
<record><start>1</start><stop>2</stop></record>
</base>

Can you think of a transformation?
In which direction I have to think?

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