How to use the pyral.hydrate.EntityHydrator function in pyral

def _createShellInstance(context, entity_name, item_name, item_ref):
    oid = item_ref.split('/').pop()
    item = {
            'ObjectID' : oid, 
            'Name'     : item_name, 
            '_type'    : entity_name,
            '_ref'     : item_ref, 
            'ref'      : '%s/%s' % (entity_name.lower(), oid)
           }
    hydrator = EntityHydrator(context, hydration="shell")
    return hydrator.hydrateInstance(item)

def hydrateAnInstance(context, item, existingInstance=None):
    global _rallyCache
    rallyContext = _rallyCache.get(context, None)
    if not rallyContext:
        # throwing an Exception is probably the correct thing to do
        return None
    hydrator = rallyContext.get('hydrator', None)
    if not hydrator:
        hydrator = EntityHydrator(context, hydration="full")
        rallyContext['hydrator'] = hydrator
    return hydrator.hydrateInstance(item, existingInstance=existingInstance)

##
##        print("%d items in the results starting at index: %d" % (self.resultCount, self.startIndex))
##

        # for whatever reason, some queries where a start index is unspecified 
        # result in the start index returned being a 0 or a 1, go figure ...
        # so we don't adjust the _servable value unless the start index is > 1
        self._servable = 0
        if self.resultCount > 0:
           self._servable = self.resultCount
           if self.startIndex > 1:
               self._servable = self.resultCount - self.startIndex
        self._servable   = min(self._servable, self._limit)
        self._served     = 0
        self._curIndex   = 0
        self.hydrator    = EntityHydrator(context, hydration=hydration)
        if self.errors:
            # transform the status code to an error code indicating an Unprocessable Entity if not already an error code
            self.status_code = 422 if self.status_code == 200 else self.status_code
##