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Missing Parameters

The missing function is used to check the status of the function arguments. It returns a boolean vector that has one element for each argument. If an element of the vector has the value T, it indicates that the corresponding argument is missing and, as a result, is filled in by a default value. The following two functions,

    func m1(...=0) missing()
    func m2(a=1,b=2,c=3,...) missing()

simply return the result of the call to missing. The result of the following invocation,

    m1(2,3,,5,)

is [F, F, T, F, T]. This indicates that the third and fifth parameters are missing. The results of the following two invocations,

    m2(2,,3,4,5)
    m2(2)

are [F, T, F, F, F] and [F, T, T] respectively. The first result indicates that only the second parameter is missing, while the second indicates that the second and third parameters are missing.

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