Retrieves the data type of an expression
See Test
Tests
function Test()
? ValType( Array( 1 ) ) --> "A"
? ValType( {|| 1 + 1 } ) --> "B"
? ValType( "HARBOUR" ) --> "C"
? ValType( Date() ) --> "D"
? ValType( .T. ) --> "L"
? ValType( 1 ) --> "N"
? ValType( TBrowse() ) --> "O"
? ValType( NIL ) --> "U"
return nil