neohelp Neo help functions Main reference https://github.com/ethereum/wiki/wiki/Patricia-Tree https://en.wikipedia.org/wiki/Radix_tree https://github.com/ethereum/aleth/blob/7e4250bf194501eb39d34e9a93edf26d78de48f5/libdevcore/TrieCommon.cpp https://github.com/ethereum/aleth/blob/7e4250bf194501eb39d34e9a93edf26d78de48f5/libdevcore/TrieDB.h