$sess->getbulk(<non-repeaters>, <max-repeaters>, <vars>)
  do an SNMP GETBULK, from the list of Varbinds, the single next lex-
  ico instance is fetched for the first n Varbinds as defined by
  <non-repeaters>. For remaining Varbinds, the m lexico instances are
  retrieved each of the remaining Varbinds, where m is
  <max-repeaters>.