init research

dataframe/plugins/kotlin-dataframe/testData/box/update.kt

@@ -0,0 +1,11 @@
+import org.jetbrains.kotlinx.dataframe.*
+import org.jetbrains.kotlinx.dataframe.annotations.*
+import org.jetbrains.kotlinx.dataframe.api.*
+import org.jetbrains.kotlinx.dataframe.io.*
+
+fun box(): String {
+    val df = dataFrameOf("a", "b")(1, null, null, "")
+    val df1 = df.update { b }.with { "empty" }
+    val b: DataColumn<String> = df1.b
+    return "OK"
+}