Example:

{1:NotNull: by *}

This will replace * with the input, if the input is not empty, e.g. ' by John' if the input was John.

The spacing is important, as you might add double spacing if you wrote something like You are being sued {1:NotNull:by *} for 10 dollars would output: You are being sued--for 10 dollars, with a double space in between 'sued' and 'for'. The by * part after the last colon should be translated to your language.

References