This defines a helper method to create the Udf.
Note that a Udf is a function which takes Columns as input and returns an derived column.
The same UDF can be applied to several columns, each applications generates an UnsafeUnaryUdfExpression as derived column.
This defines a helper method to create the Udf. Note that a Udf is a function which takes Columns as input and returns an derived column. The same UDF can be applied to several columns, each applications generates an UnsafeUnaryUdfExpression as derived column.