isZeroOrNaOrNanScalar(0)
# returns TRUE (argument is valid)
isZeroOrNaOrNanScalar("X")
# returns FALSE (argument is invalid)
#isZeroOrNaOrNanScalar("X", stopIfNot = TRUE)
# throws exception with message defined by message and argumentName parameters
isZeroOrNaOrNanScalar(0, default = NA)
# returns 0 (the argument, rather than the default, since it is not NULL)
#isZeroOrNaOrNanScalar("X", default = NA)
# throws exception with message defined by message and argumentName parameters
isZeroOrNaOrNanScalar(NULL, default = NA)
# returns NA (the default, rather than the argument, since it is NULL)
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