in src/main/scala/org/apache/spark/sql/datasketches/common/DatasketchesFunctionRegistry.scala [41:44]
protected def expression[T <: Expression : ClassTag](name: String): (String, (ExpressionInfo, FunctionBuilder)) = {
val (expressionInfo, builder) = FunctionRegistryBase.build[T](name, None)
(name, (expressionInfo, builder))
}