Return the metadata saved for a symbol.  This method is fast as it doesn't
        actually load the data.

        Parameters
        ----------
        symbol : `str`
            symbol name for the item
        as_of : `str` or int or `datetime.datetime`
            Return the data as it was as_of the point in time.
            `int` : specific version number
            `str` : snapshot name which contains the version
            `datetime.datetime` : the version of the data that existed as_of the requested point in time
        allow_secondary : `bool` or `None`
            Override the default behavior for allowing reads from secondary members of a cluster:
            `None` : use the settings from the top-level `Arctic` object used to query this version store.
            `True` : allow reads from secondary members
            `False` : only allow reads from primary members

def read_metadata(self, symbol, as_of=None, allow_secondary=None):
        """
        Return the metadata saved for a symbol.  This method is fast as it doesn't
        actually load the data.

        Parameters
        ----------
        symbol : `str`
            symbol name for the item
        as_of : `str` or int or `datetime.datetime`
            Return the data as it was as_of the point in time.
            `int` : specific version number
            `str` : snapshot name which contains the version
            `datetime.datetime` : the version of the data that existed as_of the requested point in time
        allow_secondary : `bool` or `None`
            Override the default behavior for allowing reads from secondary members of a cluster:
            `None` : use the settings from the top-level `Arctic` object used to query this version store.
            `True` : allow reads from secondary members
            `False` : only allow reads from primary members
        """
        _version = self._read_metadata(symbol, as_of=as_of, read_preference=self._read_preference(allow_secondary))
        return VersionedItem(symbol=symbol, library=self._arctic_lib.get_name(), version=_version['version'],
                             metadata=_version.pop('metadata', None), data=None,
                             host=self._arctic_lib.arctic.mongo_host)