input: Write a python function to determine if a number is odd or even.
  assert is_odd(21) == "Odd"
  assert is_odd(10) == "Even"
  assert is_odd(0) == "Even"
  assert is_odd(-5) == "Odd"
output: def is_odd(number):
      if number % 2 == 0:
          return "Even"
      else:
          return "Odd"