firstname造句
31) In this case, the function retrieves the firstName and lastName properties and puts them into an array-like structure that is then turned into a string using the join function.
32) For example, you could define a Price element that is always a floating-point number or a PersonName element that has FirstName and LastName sub-elements that are both strings.
33) In Listing 4, firstname is a string that is specified at runtime.
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