code: def _isValidTrigger(block, ch):
          
          if ch == "" or ch == "\n":
              return True # Explicit align or new line
  
          match = rxUnindent.match(block.text())
          return match is not None and \
                 match.group(3) == ""
docs: check if the trigger characters are in the right context,
          otherwise running the indenter might be annoying to the user