fix compile error of streaming project

explicit return type for implicit function

Author: James Z.M. Gao <gaozhm@mediav.com>

Closes #153 from gzm55/work/streaming-compile and squashes the following commits:

11e9c8d [James Z.M. Gao] fix style error
fe88109 [James Z.M. Gao] fix compile error of streaming project