If batchSize is 1 or negative, it will limit of number returned documents to the absolute value of
batchSize, and the cursor will be closed. For example if batchSize is -10, then the server will
return a maximum of 10 documents and as many as can fit in 4MB, then close the cursor.

Limits the number of elements returned in one batch. A cursor typically fetches a batch of result
objects and store them locally. If batchSize is positive, it represents the size of each batch of
objects retrieved. It can be adjusted to optimize performance and limit data transfer. If batchSize is
negative, it will limit of number objects returned, that fit within the max batch size limit (usually
4MB), and cursor will be closed. For example if batchSize is -10, then the server will return a
maximum of 10 documents and as many as can fit in 4MB, then close the cursor. Note that this
feature is different from limit() in that documents must fit within a maximum size, and it removes the
need to send a request to close the cursor server-side. The batch size can be changed even after a
cursor is iterated, in which case the setting will apply on the next batch retrieval.