input: from typing import List
  
  def convert_to_binary(num: int) -> str:
      """ Convert a number into binary format.
      >>> convert_to_binary(10)
      '1010'
      >>> convert_to_binary(0)
      '0'
      """
output:     if num == 0:
          return '0'
      binary_str = ''
      while num > 0:
          binary_str = str(num % 2) + binary_str
          num = num // 2
      return binary_str