October 2019
Intermediate to advanced
350 pages
9h 5m
English
Similar to the multi-level wildcard, the single-level wildcard, indicated by a plus sign (+), can be used to subscribe to various topics at once, but only one level deep. In contrast to the multi-level wildcard, it can be used at any level of the topic name—at the beginning, middle, or end. It can even be used multiple times per topic filter, as well as being combined with the multi-level wildcard. All of the following uses of single-level wildcards are valid:
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