output_description: Print the converted string in a line. Note that you do not need to convert any
  characters other than alphabetical letters.
input_description: A string is given in a line.
attempt: string = input()
  if len(string) == 1:
      print(string)
  else:
      for i in range(len(string)):
          if string[i].isupper():
              string = string.replace(string[i], string[i].lower(), 1)
          elif string[i].islower():
              string = string.replace(string[i], string[i].upper(), 1)
      print(string)
  
problem_description: Toggling Cases
  
    
  
  Write a program which converts uppercase/lowercase letters to
  lowercase/uppercase for a given string.
samples: [{"input": "fAIR, LATER, OCCASIONALLY CLOUDY.", "output": "Fair, later, occasionally cloudy."}]