>>> spark.sql("SELECT elt(1, 10, 20)").printSchema()
root
 |-- elt(1, 10, 20): string (nullable = true)

>>> spark.sql("SELECT elt(1, 10, 20)").show()
+--------------+
|elt(1, 10, 20)|
+--------------+
|            10|
+--------------+

>>> spark.sql("SELECT elt(1, 'scala', 'java')").show()
+-------------------+
|elt(1, scala, java)|
+-------------------+
|              scala|
+-------------------+

>>> spark.sql("SELECT elt(11, 10, 20)").show()
+---------------+
|elt(11, 10, 20)|
+---------------+
|           NULL|
+---------------+

>>> spark.sql("SELECT elt(6, 'scala', 'java', 'c', 'c++', 'python', 'rust')").show()
+-----------------------------------------+
|elt(6, scala, java, c, c++, python, rust)|
+-----------------------------------------+
|                                     rust|
+-----------------------------------------+

# If spark.sql.ansi.enabled is set to true, it throws ArrayIndexOutOfBoundsException for invalid indices.
