-- {% condition foo %} bar {% endcondition %}
will test the condition even though the SQL is commented out, and will generate an error if the filter foo doesn’t exist. Of course, you can instead put the obsolete condition in a LookML comment
# formerly at line 42: {% condition foo %} bar {% endcondition %}
after the SQL. But sometimes it’s nice to have them in a particular spot within the SQL. You can use
-- {[]% condition foo %} bar {[]% endcondition %}
or the like so Looker doesn’t test the condition.