def load(filename, ureg='pimms'):
    '''
    pimms.load(filename) loads a pimms-formatted save-file from the given filename, which may
      optionaly be a string. By default, this function forces all quantities (via the pint
      module) to be loaded using the pimms.units unit registry; the option ureg can change
      this.

    If the filename is not a correctly formatted pimms save-file, an error is raised.

    Options:
      * ureg ('pimms') specifies the unit-registry to use for ping module units that are loaded
        from the files; 'pimms' is equivalent to pimms.units. None is equivalent to using the
        pint._APP_REGISTRY unit registry.
    '''
    if ureg is not None:
        if ureg == 'pimms': ureg = units
        orig_app_ureg = pint._APP_REGISTRY
        orig_dfl_ureg = pint._DEFAULT_REGISTRY
        pint._APP_REGISTRY = ureg
        pint._DEFAULT_REGISTRY = ureg
        try:    return load(filename, ureg=None)
        except: raise
        finally:
            pint._APP_REGISTRY     = orig_app_ureg
            pint._DEFAULT_REGISTRY = orig_dfl_ureg
    if isinstance(filename, six.string_types):
        filename = os.path.expanduser(filename)
        with open(filename, 'rb') as f:
            return _load_stream(f)
    else:
        return _load_stream(filename)