Added docs in a couple of files, added multiple conversions regarding tuples, pairs, arities etc.

Author: Jolanrensen

…etbrains/kotlinx/spark/api/VarArities.kt …g/jetbrains/kotlinx/spark/api/Arities.ktkotlin-spark-api/3.2/src/main/kotlin/org/jetbrains/kotlinx/spark/api/VarArities.kt renamed to kotlin-spark-api/3.2/src/main/kotlin/org/jetbrains/kotlinx/spark/api/Arities.kt kotlin-spark-api/3.2/src/main/kotlin/org/jetbrains/kotlinx/spark/api/VarArities.kt renamed to kotlin-spark-api/3.2/src/main/kotlin/org/jetbrains/kotlinx/spark/api/Arities.kt

@@ -17,9 +17,30 @@
  * limitations under the License.
  * =LICENSEEND=
  */
+
 /**
- * Helper classes and functions to work with unnamed tuples
+ * Helper classes and functions to work with unnamed tuples we call Arities.
+ * Arities are easier to work with in Kotlin than Scala Tuples since they are Kotlin data classes.
+ * This means they can be destructured, copied, etc.
+ * Finally, the Arities are Serializable, meaning they can be used inside RDDs and they can be broadcast.
+ *
+ * Example:
+ * ```kotlin
+ * // creation
+ * val tuple: Arity3<Int, String, Double> = c(1, "test", 1.0)
+ *
+ * // addition
+ * val newTuple: Arity5<Int, String, Double, Int, Int> = tuple + c(1, 2)
+ *
+ * // destructuring
+ * val dataset: Dataset<Arity2<Int, Double>> = ...
+ * dataset.map { (a: Int, b: Double) ->
+ *    (a + b).toString()
+ * }
+ *
+ * ```
  */
+
 package org.jetbrains.kotlinx.spark.api
 
 import java.io.Serializable

kotlin-spark-api/3.2/src/main/kotlin/org/jetbrains/kotlinx/spark/api/Column.kt

@@ -1,3 +1,28 @@
+/*-
+ * =LICENSE=
+ * Kotlin Spark API: API for Spark 3.0+ (Scala 2.12)
+ * ----------
+ * Copyright (C) 2019 - 2021 JetBrains
+ * ----------
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * =LICENSEEND=
+ */
+
+/**
+ * This file contains all Column helper functions.
+ * This includes easier Column creation and operator functions.
+ */
+
 package org.jetbrains.kotlinx.spark.api
 
 import org.apache.spark.sql.Column