Convert a list resulting from the checks performed in a
checkFunction into a checkResult object, thereby
supplying it with a print() method.
checkResult(ls)A S3 object of class checkResult, identical to the inputted
list, ls, except for its class attribute.
A list with entries $problem (logical indicating whether
a problem was found), $message (a character string containing a
message describing the problem) and $problemValues (the values
in the checked variables that were marked as problematic). Note that
$message and $problemValues can be left empty (i.e.
"" and NULL, respectively), if they are not relevant.
checkFunction