Exercise 1: Adapting a Pence-Based Legacy Gateway — Possible Solution
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THE NEW ADAPTER, FOLLOWING THIS CHAPTER'S OWN TEMPLATE
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    class LegacyGateway2:
        def process(self, total_pence):
            return f'Legacy2 processed {total_pence} pence'

    class PaymentGatewayAdapter2:
        def __init__(self, legacy_gateway):
            self._legacy_gateway = legacy_gateway
        def pay(self, amount_dollars):
            total_pence = round(amount_dollars * 100)
            return self._legacy_gateway.process(total_pence)

This mirrors this chapter's own PaymentGatewayAdapter exactly - the
same wrap-and-translate shape, with the target method name (process
instead of make_payment) and parameter name (total_pence instead of
amount_cents) changed to match this specific legacy gateway's own
interface, and the same dollars-to-hundredths conversion reused, since
both cents and pence are hundredths of their respective currency
units.

VERIFYING THE CONVERSION AND THE UNMODIFIED checkout() CALL
------------------------------
Calling checkout(PaymentGatewayAdapter2(LegacyGateway2()), 19.99)
returns 'Legacy2 processed 1999 pence' - confirming 19.99 dollars
correctly became 1999 pence (19.99 * 100 = 1999), and confirming the
exact same checkout() function from this chapter, completely
unmodified, works correctly with this second, differently-shaped
legacy gateway.

WHY THIS CONFIRMS ADAPTER'S OWN GENERAL-PURPOSE VALUE
------------------------------
This chapter's own client function, checkout(), never needed to
change to support this second, differently-named, differently-shaped
legacy interface - only a new, small, self-contained adapter class was
needed, exactly mirroring the same zero-change-to-existing-code
benefit this course established as far back as Chapter 1.

WHY THIS WORKS AS AN ANSWER
------------------------------
The new adapter class is built by directly mirroring this chapter's
own established template, adjusted only where the target interface's
own method and parameter names genuinely differ, and the result is
verified both for the specific numeric conversion and for successful,
unmodified reuse of the existing checkout() function.