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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 load_stock_quantity(self, symbol: str) -> Decimal(0):
 """ retrieves stock quantity """

        book = self.get_gc_book()

        collection = SecuritiesAggregate(book)
        sec = collection.get_aggregate_for_symbol(symbol)
        quantity = sec.get_quantity()
        return quantity