Understanding Mersenne Twister Code Implementation - Python

I'am having trouble understanding this code from http://ift.tt/1SDESKn

def _int32(x):
# Get the 32 least significant bits.  
   return int(0xFFFFFFFF & x)

class MT19937:

def __init__(self, seed):
    # Initialize the index to 0
    self.index = 624
    self.mt = [0] * 624
    self.mt[0] = seed  # Initialize the initial state to the seed
    for i in range(1, 624):
        self.mt[i] = _int32(
            1812433253 * (self.mt[i - 1] ^ self.mt[i - 1] >> 30) + i)

def extract_number(self):
    if self.index >= 624:
        self.twist()

    y = self.mt[self.index]

    # Right shift by 11 bits
    y = y ^ y >> 11
    # Shift y left by 7 and take the bitwise and of 2636928640
    y = y ^ y << 7 & 2636928640
    # Shift y left by 15 and take the bitwise and of y and 4022730752
    y = y ^ y << 15 & 4022730752
    # Right shift by 18 bits
    y = y ^ y >> 18

    self.index = self.index + 1

    return _int32(y)

def twist(self):
    for i in range(624):
        # Get the most significant bit and add it to the less significant
        # bits of the next number
        y = _int32((self.mt[i] & 0x80000000) +
                   (self.mt[(i + 1) % 624] & 0x7fffffff))
        self.mt[i] = self.mt[(i + 397) % 624] ^ y >> 1

        if y % 2 != 0:
            self.mt[i] = self.mt[i] ^ 0x9908b0df
    self.index = 0
    #test

I would really appreciate any help. How do i generate the number and print them ? How do i "generate" the parameter seed for the class? What does def _int32(x) contribute?