fix tunnel close bug & add a cli example

[piaodazhu]

No description provided.

[codecov]

Codecov Report

Merging #13 (4b688f5) into master (b9fa7a0) will decrease coverage by 0.09%.
Report is 15 commits behind head on master.
The diff coverage is 0.00%.

❗ Current head 4b688f5 differs from pull request most recent head ca3ebfa. Consider uploading reports for the commit ca3ebfa to get more accurate results

@@            Coverage Diff             @@
##           master      #13      +/-   ##
==========================================
- Coverage   73.70%   73.61%   -0.09%     
==========================================
  Files           6        6              
  Lines         867      868       +1     
==========================================
  Hits          639      639              
- Misses        166      167       +1     
  Partials       62       62              

Files	Coverage Δ
server.go	77.71% <0.00%> (-0.22%)	⬇️