Add samples for last() and lastOrNull() functions

libraries/stdlib/samples/test/samples/collections/collections.kt

@@ -800,6 +800,19 @@ class Collections {
             val emptyList = emptyList<Int>()
             assertPrints(emptyList.getOrNull(0), "null")
         }
+
+        @Sample
+        fun last() {
+            val list = listOf(1, 2, 3, 4)
+            assertPrints(list.last(), "4")
+            assertPrints(list.last { it % 2 == 1 }, "3")
+            assertPrints(list.lastOrNull { it < 0 }, "null")
+            assertFails { list.last { it < 0 } }
+
+            val emptyList = emptyList<Int>()
+            assertPrints(emptyList.lastOrNull(), "null")
+            assertFails { emptyList.last() }
+        }
     }
 
     class Sorting {

libraries/stdlib/samples/test/samples/text/strings.kt

@@ -408,4 +408,17 @@ class Strings {
         assertPrints(matchDetails(inputString, toFind, 2), "Searching for 'ever' in 'Never ever give up' starting at position 2: Found at 6")
         assertPrints(matchDetails(inputString, toFind, 10), "Searching for 'ever' in 'Never ever give up' starting at position 10: Not found")
     }
+
+    @Sample
+    fun last() {
+        val string = "Kotlin 1.4.0"
+        assertPrints(string.last(), "0")
+        assertPrints(string.last { it.isLetter() }, "n")
+        assertPrints(string.lastOrNull { it > 'z' }, "null")
+        assertFails { string.last { it > 'z' } }
+
+        val emptyString = ""
+        assertPrints(emptyString.lastOrNull(), "null")
+        assertFails { emptyString.last() }
+    }
 }