define_command
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@34669 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
define_commandAPI. Patch from 7rans transfire@gmail.comgit-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@34669 b2dd03c8-39d4-4d8f-98ff-823fe69b080e