bson_iter_binary(3) on Linux
The text e1db415c228a, as Debian 9 (Stretch) shipped it.
This function shall return the binary data of a BSON_TYPE_BINARY element. It is a programming error to call this function on a field that is not of type BSON_TYPE_BINARY. You can check this with the BSON_ITER_HOLDS_BINARY() macro or bson_iter_type().