conditional if
$if{expr} ... $elif{expr} ... $else ... $fi
The conditional if/elif/else construct,
apart from the closing $fi,
behaves just like you would expect i.e. as in python,
with optional (multiple) $elif{}'s and an optional
concluding $else.
The condition expression may be any python expression, that must evaluate without errors in the supplied namespace. As for all directives, being on a single line or spanning many lines has no relevance.