docs: def method_cache(method, cache_wrapper=None):
  	"""
  	Wrap lru_cache to support storing the cache data in the object instances.
  
  	Abstracts the common paradigm where the method explicitly saves an
  	underscore-prefixed protected property on first call and returns that
  	subsequently.
  
  	>>> class MyClass:
  	...     calls = 0
  	...
  	...     @method_cache
  	...     def method(self, value):
  	...         self.calls += 1
  	...         return value
  
  	>>> a = MyClass()
  	>>> a.method(3)
  	3
  	>>> for x in range(75):
  	...     res = a.method(x)
  	>>> a.calls
  	75
  
  	Note that the apparent behavior will be exactly like that of lru_cache
  	except that the cache is stored on each instance, so values in one
  	instance will not flush values from another, and when an instance is
  	deleted, so are the cached values for that instance.
  
  	>>> b = MyClass()
  	>>> for x in range(35):
  	...     res = b.method(x)
  	>>> b.calls
  	35
  	>>> a.method(0)
  	0
  	>>> a.calls
  	75
  
  	Note that if method had been decorated with ``functools.lru_cache()``,
  	a.calls would have been 76 (due to the cached value of 0 having been
  	flushed by the 'b' instance).
  
  	Clear the cache with ``.cache_clear()``
  
  	>>> a.method.cache_clear()
  
  	Another cache wrapper may be supplied:
  
  	>>> cache = lru_cache(maxsize=2)
  	>>> MyClass.method2 = method_cache(lambda self: 3, cache_wrapper=cache)
  	>>> a = MyClass()
  	>>> a.method2()
  	3
  
  	Caution - do not subsequently wrap the method with another decorator, such
  	as ``@property``, which changes the semantics of the function.
  
  	See also
  	http://code.activestate.com/recipes/577452-a-memoize-decorator-for-instance-methods/
  	for another implementation and additional justification.
  	"""
  	cache_wrapper = cache_wrapper or lru_cache()
  
  	def wrapper(self, *args, **kwargs):
  		# it's the first call, replace the method with a cached, bound method
  		bound_method = types.MethodType(method, self)
  		cached_method = cache_wrapper(bound_method)
  		setattr(self, method.__name__, cached_method)
  		return cached_method(*args, **kwargs)
  
  	return _special_method_cache(method, cache_wrapper) or wrapper