inputs <- as.Date(c("2007-01-01",
                     "2007-01-31",
                     "2008-02-01",
                     "2008-02-29",
                     "2008-03-14",
                     "2008-12-01",
                     "2008-12-31"))
 expected.outputs <- as.Date(c("2007-01-31",
                              "2007-01-31",
                              "2008-02-29",
                              "2008-02-29",
                              "2008-03-31",
                              "2008-12-31",
                              "2008-12-31"))
 LastDayInMonth(inputs) == expected.outputs
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