class RSpec::Core::Backports::Random::MT19937

def seed=(seed)

No conversion or type checking is done at this level

or an Array of Integers (of which only the first 32 bits will be used)
Seed must be either an Integer (only the first 32 bits will be used) 
def seed=(seed)
  case seed
  when Integer
    @state = Array.new(STATE_SIZE)
    @state[0] = seed & PAD_32_BITS
    (1..LAST_STATE).each do |i|
      @state[i] = (1812433253 * (@state[i-1]  ^ @state[i-1]>>30) + i)& PAD_32_BITS
    end
    @last_read = LAST_STATE
  when Array
    self.seed = 19650218
    i=1
    j=0
    [STATE_SIZE, seed.size].max.times do
      @state[i] = (@state[i] ^ (@state[i-1] ^ @state[i-1]>>30) * 1664525) + j + seed[j] & PAD_32_BITS
      if (i+=1) >= STATE_SIZE
        @state[0] = @state[-1]
        i = 1
      end
      j = 0 if (j+=1) >= seed.size
    end
    (STATE_SIZE-1).times do
      @state[i] = (@state[i] ^ (@state[i-1] ^ @state[i-1]>>30) * 1566083941) - i & PAD_32_BITS
      if (i+=1) >= STATE_SIZE
        @state[0] = @state[-1]
        i = 1
      end
    end
    @state[0] = 0x80000000
  else
    raise ArgumentError, "Seed must be an Integer or an Array"
  end
end