input: Write a python function to convert an integer to its binary representation.
  assert integer_to_binary(10) == '1010'
  assert integer_to_binary(0) == '0'
  assert integer_to_binary(-1) == '11111111111111111111111111111111'
  assert integer_to_binary(255) == '11111111'
  assert integer_to_binary(-10) == '11111111111111111111111111110110'
output: def integer_to_binary(n):
      if n >= 0:
          return bin(n)[2:]
      else:
          return bin(n & 0xffffffff)[2:]