Format column number Excel like to a cell letter

column_converter.py

def get_column_letter(column_no):
  """
  A = 0
  Z = 25
  AA = 26
  AB = 27
  BA = 52
  :param column_no: The 0-based column index.
  :return: The column as a combination of letters.
  """
  stack = []

  output = ""
  while column_no > -1:
      stack.append(column_no % len(self.alphabet))
      column_no = column_no / len(self.alphabet) - 1
  while len(stack) > 0:
      output += self.alphabet[stack.pop()]
  return output