remove unneeded type constraint; this makes restore_key method 50-100ns faster (5-15% improvement)
remove unneeded type constraint; this makes restore_key method 50-100ns faster (5-15% improvement)

nervenXC/marisa-trie,kmike/marisa-trie,pombredanne/marisa-trie,pombredanne/marisa-trie,kmike/marisa-trie,kmike/marisa-trie,pytries/marisa-trie,nervenXC/marisa-trie,nervenXC/marisa-trie,pytries/marisa-trie,nervenXC/marisa-trie,kmike/marisa-trie