code: def mute_string(text):
      
      # String modifiers (e.g. u or r)
      start = text.index(text[-1]) + 1
      end = len(text) - 1
      # Triple quotes
      if text[-3:] in ('"""', "'''"):
          start += 2
          end -= 2
      return text[:start] + 'x' * (end - start) + text[end:]
docs: Replace contents with 'xxx' to prevent syntax matching.
  
      >>> mute_string('"abc"')
      '"xxx"'
      >>> mute_string("'''abc'''")
      "'''xxx'''"
      >>> mute_string("r'abc'")
      "r'xxx'"