add ExampleEncode function

[huangqian1985]

今天写文档的时候发现漏了一个Example

[codecov-commenter]

Codecov Report

Merging #1795 (3628b1e) into master (793e862) will decrease coverage by 0.08%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #1795      +/-   ##
==========================================
- Coverage   71.27%   71.19%   -0.09%     
==========================================
  Files         452      459       +7     
  Lines       43336    43571     +235     
==========================================
+ Hits        30889    31019     +130     
- Misses      10470    10560      +90     
- Partials     1977     1992      +15     

Flag	Coverage Δ
go-1.15	71.17% <ø> (-0.09%)	⬇️
go-1.16	71.13% <ø> (-0.12%)	⬇️
go-1.17	71.15% <ø> (-0.11%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
database/gdb/gdb_core_ctx.go	60.86% <0.00%> (-31.44%)	⬇️
os/glog/glog_logger_level.go	40.00% <0.00%> (-24.00%)	⬇️
os/gsession/gsession_storage_file.go	45.96% <0.00%> (-16.54%)	⬇️
os/gsession/gsession_storage_memory.go	76.92% <0.00%> (-14.75%)	⬇️
errors/gerror/gerror_error.go	61.44% <0.00%> (-4.25%)	⬇️
util/guid/guid.go	88.23% <0.00%> (-4.08%)	⬇️
database/gdb/gdb_model_update.go	76.62% <0.00%> (-2.25%)	⬇️
database/gdb/gdb_model_cache.go	64.86% <0.00%> (-1.81%)	⬇️
os/gsession/gsession_session.go	56.63% <0.00%> (-1.63%)	⬇️
os/gview/gview_buildin.go	91.07% <0.00%> (-1.62%)	⬇️
... and 40 more

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