def set(i)
      check_range(i)
      w = self.word_index(i)
      result = @words[w] |= (1 << (i % BITS_PER_WORD))
      result
    end
def set(i)
      check_range(i)
      w = self.word_index(i)
      result = @words[w] |= (1 << (i % BITS_PER_WORD))
      result
    end
@param [Integer] Number of bits in the set
 @api public
 initialize(nbits)
 Sets (flags) given bit. This method allows bits to be set more than once in a row, no exception will be raised.

 @param [Integer] A bit to set
 @api public