Mitchell is the principal owner of Samuel Mitchell, Inc., a real estate firm. Mitchell signed an exclusive brokerage agreement with Newsome to find a purchaser for Newsome's property within ninety days. This type of agreement entitles the broker to a commission if the property is sold to any purchaser to whom it is shown during the ninety-day period. Newsome tried to cancel the brokerage agreement before the ninety-day term had expired. Mitchell had already advertised the property, put up a "for sale" sign, and shown the property to prospective buyers. Newsome claimed that the brokerage contract was unilateral and that she could cancel at any time before Mitchell found a buyer. Mitchell claimed that the contract was bilateral and that Newsome's cancellation breached the contract. Discuss who should prevail at trial.