input: def convert_to_binary(num):
      """
      Generate a code in Python to convert a number into binary format.
      
      >>> convert_to_binary(10)
      '1010'
      >>> convert_to_binary(0)
      0
      >>> convert_to_binary(7)
      '111'
      >>> convert_to_binary(255)
      '11111111'
      """
      if num == 0:
          return 0
      
      binary = ''
      
      while num != 0:
          remainder = num % 2
          binary = str(remainder) + binary
          num = num // 2
      
      return binary
output:     if num == 0:
          return 0
      
      binary = ''
      
      while num != 0:
          remainder = num % 2
          binary = str(remainder) + binary
          num = num // 2
      
      return binary