new_contents: import re
  
  ALPHA = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
  
  def spreadsheet(s):
      if re.fullmatch('[A-Z]+\d+', s):
          return 'R' + re.findall('\d+', s)[0] + 'C' + from_base_26(re.findall('[A-Z]+', s)[0])
      else:
          return to_base_26(re.findall('\d+', s)[1]) + re.findall('\d+', s)[0]
  
  
  def to_base_26(num):
  
      num    = int(num)
      result = ''
      if num < 26:
          return ALPHA[num-1]
      
      while num > 0:
          if num % 26 == 0: 
              result += 'Z'; num = int(num / 26) - 1
          else:
              result += ALPHA[(num % 26) - 1]; num = int(num / 26)
      
      return result[::-1]
  
  
  def from_base_26(s):
      result = 0
      for i,n in enumerate(str(s)[::-1]):
          result += (ALPHA.index(n)+1) * 26**i
      return str(result)
  
subject: Create 5kyu_simple_fun_spreadsheet.py