code: def _check_str_value(x):
      
      if isinstance(x, str):
          # remove commas, and single quotation marks since loadarff cannot deal with it
          x = x.replace(",", ".").replace(chr(0x2018), "'").replace(chr(0x2019), "'")
  
          # put string in double quotes
          if " " in x:
              if x[0] in ('"', "'"):
                  x = x[1:]
              if x[-1] in ('"', "'"):
                  x = x[:len(x) - 1]
              x = '"' + x.replace('"', "\\\"") + '"'
      return str(x)
docs: If string has a space, wrap it in double quotes and remove/escape illegal characters