code: func WithBuffer(n int) JSONSourceOption {
  	return func(j *JSONSource) {
  		if n > -1 {
  			j.records = make(chan record, n)
  		}
  	}
  }
docs: // WithBuffer is an option for JSONSource which modifies the length of the
  // channel used to buffer received records (while they are waiting to be
  // retrieved by a call to Record).