docs: def get_mask_description(self):
          '''
          Return an ASCII string describing the mask field in terms of
          bitwise-or'd IN_* constants, or 0.  The result is valid Python code
          that could be eval'd to get the value of the mask field.  In other
          words, for a given event:
  
          >>> from inotifyx import *
          >>> assert (event.mask == eval(event.get_mask_description()))
          '''
  
          parts = []
          for name, value in list(constants.items()):
              if self.mask & value:
                  parts.append(name)
          if parts:
              return '|'.join(parts)
          return '0'