code: public static BitVector fromStore(BitStore store) {
  		if (store instanceof BitVector) return ((BitVector)store).mutableCopy();
  		if (store == null) throw new IllegalArgumentException("null store");
  		return new BitVector(store);
  	}
docs: Creates a {@link BitVector} by copying another {@link BitStore}.
  
  @param store
  the bit store to be copied
  @return a new bit vector that equals the supplied store