[enh] add a new test for middle insertion
[mod] update TODO
[enh] test EndlProxy.append
[enh] test and fix EndlProxy.pop
[enh] test EndlProxy.__delitem__
[mod] update TODO
[enh] test EndlProxy.remove
[enh] test EndlProxy.__setitem__
[fix] CodeBlockNode actually do things at that level
[enh] test EndlProxy.__setslice__
[enh] test EndlProxy.__delslice__
[enh] test EndlProxy.__getslice__
[enh] test EndlProxy.extend
[mod] remove unappriopriate todo test
[fix] fix test due to proxyfication of EndlProxyNode