bson_append_array_begin(3) on Linux
The text 0ff7335907e2, as Debian 9 (Stretch) shipped it.
The bson_append_array_begin() function shall begin appending an array field to bson. This allows for incrementally building a sub-array. Doing so will generally yield better performance as you will serialize to a single buffer. When done building the sub-array, the caller MUST call bson_append_array_end().