input: Write a function to convert a given integer to a specified base.
  assert conv_to_base(10, 2) == "1010"
  assert conv_to_base(255, 16) == "ff"
  assert conv_to_base(100, 8) == "144"
output: def conv_to_base(number, base):
      if number == 0:
          return "0"
      
      digits = "0123456789abcdefghijklmnopqrstuvwxyz"
      result = ""
      
      while number > 0:
          result = digits[number % base] + result
          number //= base
      
      return result