old_contents: import collections
  import typing
  
  
  class Meta(collections.OrderedDict, typing.MutableMapping[str, float]):
    def __init__(self, *args, **kwargs) -> None:
      self._smallest = float('inf')
      self._largest = 0
      self._ordered = True
      super(Meta, self).__init__(*args, **kwargs)
  
    def __setitem__(self, key: str, value: float) -> None:
      if key in self and self[key] == value:
        raise AssertionError('Redundant assignment: %s = %s' % (key, value))
      if value > self._smallest:
        self._ordered = False
      else:
        self._smallest = value
      if value > self._largest:
        self._largest = value
      super(Meta, self).__setitem__(key, value)
      self._changed()
  
    def items(self) -> typing.ItemsView[str, float]:
      self._reorder()
      return super(Meta, self).items()
  
    def first(self) -> typing.Tuple[str, float]:
      self._reorder()
      for k, v in self.items():
        return k, v
  
    def peek(self) -> str:
      self._reorder()
      for first in self:
        return first
  
    def magnitude(self) -> float:
      return self._largest
  
    def _reorder(self) -> None:
      if self._ordered:
        return
      order = sorted(super(Meta, self).items(), key=lambda x: x[1], reverse=True)
      for k, v in order:
        self.move_to_end(k)
      self._ordered = True
  
    def _changed(self):
      pass
  
new_contents: import collections
  import typing
  from typing import TypeVar
  
  Key = TypeVar('Key')
  
  
  class Meta(collections.OrderedDict, typing.MutableMapping[Key, float]):
    def __init__(self, *args, **kwargs) -> None:
      self._smallest = float('inf')
      self._largest = 0
      self._ordered = True
      super(Meta, self).__init__(*args, **kwargs)
  
    def __setitem__(self, key: Key, value: float) -> None:
      if key in self and self[key] == value:
        raise AssertionError('Redundant assignment: %s = %s' % (key, value))
      if value > self._smallest:
        self._ordered = False
      else:
        self._smallest = value
      if value > self._largest:
        self._largest = value
      super(Meta, self).__setitem__(key, value)
      self._changed()
  
    def items(self) -> typing.ItemsView[Key, float]:
      self._reorder()
      return super(Meta, self).items()
  
    def first(self) -> typing.Tuple[Key, float]:
      self._reorder()
      for k, v in self.items():
        return k, v
  
    def peek(self) -> Key:
      self._reorder()
      for first in self:
        return first
  
    def magnitude(self) -> float:
      return self._largest
  
    def _reorder(self) -> None:
      if self._ordered:
        return
      order = sorted(super(Meta, self).items(), key=lambda x: x[1], reverse=True)
      for k, v in order:
        self.move_to_end(k)
      self._ordered = True
  
    def _changed(self) -> None:
      pass
  
subject: Improve typing on Meta.