Is the variable empty (Null, or empty string) ? This is named in the tradition of very short, much used functions like nz() and iif(). Pronounce 'Em Tee', and we use this name because Empty and IsEmpty() are already taken in VBA.
A variant value
Suppress error if an error occurs
If the varToTest is a string, trim spaces before testing
mt(Null) => True
mt("") => True
mt("0") => False
mt(0) => False
mt(23) => False
mt(False) => False