def get_students(students):
    """Get students documents from es generator.
    """
    for j in range(0, len(students), BATCH):
        for student in Search(using=client).doc_type(
            "student_document"
        ).query(
            "simple_query_string",
            query=" ".join(
                "{}".format(i) for i in students[j:j+BATCH]
            ),
            fields=['id'],
            default_operator="OR"
        )[:BATCH]:
            yield student.to_dict()