code: def _make_one_char_uppercase(string: str) -> str:
          
          if not isinstance(string, str):
              raise TypeError('string must be a string')
  
          if Aux.lowercase_count(string) > 0:
              while True:
                  cindex = randbelow(len(string))
                  if string[cindex].islower():
                      aux = list(string)
                      aux[cindex] = aux[cindex].upper()
                      string = ''.join(aux)
                      break
  
          return string
docs: Make a single char from the string uppercase.