docs: function fillCollection(collection, max, callback) {
      collection.count(function(err,count) {
          console.log(collection+" count = "+count)
          while (count < max) {
              var toInsert = []
              while (count < max) {
                  toInsert.push({ foo: Math.random(), index: count++ })
                  if (toInsert.length == 300) {
                      break
                  }
              }
              console.log("inserting "+toInsert.length+" document(s) into "+collection)
              collection.insert(toInsert)
          }
          callback()
      })
  }