Wong retired as a partner from a firm, where he was a partner for 20 years. Upon his retirement he posted his notice of retirement on the notice board of the firm. Several months later, his former firm borrowed money from one of their customers. The customer and the former partners executed a loan document. The firm failed to pay loan and the customer sued the partnership firm and Wong's name was included in the legal suit. Advise Wong regarding his liability as a former partner.