then keyword in control flows 'if' and 'select'

## Description

Used in control flows `if` and `select`. Each `then` keyword must be on the same line as its corresponding `if`, `elseif` or `case` keyword.

The keyword `then` can be replaced by a carriage return or a comma.

## Examples

    if 2*2 == 4 then
       disp("It works")
    end

    n=round(10*rand(1,1))
    select n
        case 0 then
            disp(0)
        case 1 then
            disp(1)
        else
          disp(n);
    end

## See also

- if
- elseif
- select
- case

## History

6.0.0 `then` is now protected: Assignments like `then=1` are no longer possible.