Minor Description
Support data masking built-in Function mask
Return a masked version of str. By default, upper case letters should be converted to "X", lower case letters should be converted to "x" and numbers should be converted to "n". For example mask("abcd-EFGH-8765-4321") results in xxxx-XXXX-nnnn-nnnn. Should be able override the characters used in the mask by supplying additional arguments: the second argument controls the mask character for upper case letters, the third argument for lower case letters and the fourth argument for numbers. For example, mask("abcd-EFGH-8765-4321", "U", "l", "#") should result in llll-UUUU-####-####
