code: def phrase_contains_special_keys(expansion: model.Expansion) -> bool:
          
          found_special_keys = KEY_FIND_RE.findall(expansion.string.lower())
          return bool(found_special_keys)
docs: Determine if the expansion contains any special keys, including those resulting from any processed macros
          (<script>, <file>, etc). If any are found, the phrase cannot be undone.
  
          Python Zen: »In the face of ambiguity, refuse the temptation to guess.«
          The question 'What does the phrase expansion "<ctrl>+a<shift>+<insert>" do?' cannot be answered. Because the key
          bindings cannot be assumed to result in the actions "select all text, then replace with clipboard content",
          the undo operation can not be performed. Thus always disable undo, when special keys are found.