docs: def time_methods(obj, methods, prefix=None):
      """
      Patch obj so calls to given methods are timed
  
      >>> class C(object):
      ...     def m1(self):
      ...         return 'ok'
      ...
      ...     def m2(self, arg):
      ...         return arg
      ...
      >>> c = C()
      >>> time_methods(c, ['m1', 'm2'])
      >>> c.m1()
      'ok'
      >>> c.m2('ok')
      'ok'
      >>> c = C()
      >>> time_methods(c, ['m1'], 'mymetrics')
      """
      if prefix:
          prefix = prefix + '.'
      else:
          prefix = ''
  
      for method in methods:
          current_method = getattr(obj, method)
          new_method = timed(prefix)(current_method)
          setattr(obj, method, new_method)