Write TCP chat server and its unit tests
Merge pull request #19 from oshothebig/goken14

Goken 14の課題
バグってる
Merge pull request #20 from saiias/saiias-chatserver

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simple test for chat server goken 14
Merge pull request #21 from jbking/master

simple test for chat server goken 14
the handle func become Client.Join
add type checking.
Merge pull request #22 from jbking/master

the handle func become Client.Join
add goken15 課題
Merge branch 'master' of github.com:goken/goken
update kadai 15