def perform_es_search(q, index, start=0, size=10, sort=None, fields=None):
"""Helper to use elasticsearch_dsl with Spires/Invenio syntax."""
query = IQ(q)
search = RecordsSearch(index=index).query(query)
if sort:
search = search.sort(sort)
if fields and isinstance(fields, list):
search = search.extra(_source={'include': fields})
return search[start:start + size].execute()
