def build_permuted_index(<EOL>self,<EOL>lshash,<EOL>buckets,<EOL>num_permutation,<EOL>beam_size,<EOL>num_neighbour):
<EOL>pi = PermutedIndex(<EOL>lshash,<EOL>buckets,<EOL>num_permutation,<EOL>beam_size,<EOL>num_neighbour)<EOL>hash_name = lshash.hash_name<EOL>self.permutedIndexs[hash_name] = pi<EOL>
Build a permutedIndex and store it into the dict self.permutedIndexs.
lshash: the binary lshash object (nearpy.hashes.lshash).
buckets: the buckets object corresponding to lshash. It's a dict object 
         which can get from nearpy.storage.buckets[lshash.hash_name]
num_permutation: the number of sorted randomly-permuted bucket key lists (SRPBKL).
beam_size: beam size, details please refer to __init__() in nearpy.hashes.permutation.PermutedIndex 
num_neighbour: the number of neighbour bucket keys needed to return in self.get_neighbour_keys().