code: def unfreeze(label, pop=False, environ=None):
      
  
      environ = os.environ if environ is None else environ
      diff = _get_diff(environ, label, pop=pop)
      original = _apply_diff(environ, diff)
      return _refreezer(environ, diff, original)
docs: Reset the environment to its state before it was frozen by :func:`freeze`.
  
      :param str label: The name for the frozen environment.
      :param bool pop: Destroy the freeze after use; only allow unfreeze once.
      :param dict environ: The environment to work on; defaults to ``os.environ``.
      :returns: A context manager to re-freeze the environment on exit.
  
      Usage::
  
          unfreeze('nuke')
  
          # or
  
          with unfreeze('maya'):
              # do something