Support Iterables in general in array_get

Author: LadyCailin

src/main/java/com/laytonsmith/core/functions/ArrayHandling.java

@@ -263,13 +263,13 @@ public Mixed exec(Target t, Environment env, Mixed... args) throws ConfigRuntime
 						throw e;
 					}
 				}
-			} else if(args[0].isInstanceOf(ArrayAccess.TYPE)) {
+			} else if(args[0].isInstanceOf(com.laytonsmith.core.natives.interfaces.Iterable.TYPE)) {
 				com.laytonsmith.core.natives.interfaces.Iterable aa
 						= (com.laytonsmith.core.natives.interfaces.Iterable) args[0];
-				if(index instanceof CSlice) {
+				if(index instanceof CSlice cSlice) {
 					//It's a range
-					int start = (int) ((CSlice) index).getStart();
-					int finish = (int) ((CSlice) index).getFinish();
+					int start = (int) cSlice.getStart();
+					int finish = (int) cSlice.getFinish();
 					try {
 						//Convert negative indexes
 						if(start < 0) {
@@ -288,7 +288,7 @@ public Mixed exec(Target t, Environment env, Mixed... args) throws ConfigRuntime
 					return aa.get(index, t);
 				}
 			} else {
-				throw new CRECastException("Argument 1 of " + this.getName() + " must be an array", t);
+				throw new CRECastException("Argument 1 of " + this.getName() + " must be an Iterable object, such as an array.", t);
 			}
 		}
 

src/main/java/com/laytonsmith/core/natives/interfaces/ArrayAccess.java

@@ -78,6 +78,17 @@ public interface ArrayAccess extends Booleanish {
 
 	/**
 	 * Returns a slice at the specified location. Should throw an exception if an element in the range doesn't exist.
+	 * The range is inclusive.
+	 *
+	 * @implNote In general, MethodScript supports undefined begin and end slices, as well as reverse slices. For
+	 * CArray type only, this is fully covered, but for other slice types, only negative slice numbers are converted,
+	 * and subclasses must handle both forward and reverse slices if applicable. A good way to handle that is as such:
+	 * <pre><code>
+	 * int start = Math.min(begin, end);
+	 * int stop = Math.max(begin, end);
+	 * int step = (begin &lt;= end) ? 1 : -1;
+	 * for (int i = start; i != stop; i += step) { ... }
+	 * </code></pre>
 	 *
 	 * @param begin
 	 * @param end