Move ToArea to extension method

Sharp7.Rx/Extensions/OperandExtensions.cs

@@ -0,0 +1,17 @@
+using Sharp7.Rx.Enums;
+
+namespace Sharp7.Rx.Extensions;
+
+internal static class OperandExtensions
+{
+    public static S7Area ToArea(this Operand operand) =>
+        operand switch
+        {
+            Operand.Input => S7Area.PE,
+            Operand.Output => S7Area.PA,
+            Operand.Marker => S7Area.MK,
+            Operand.Db => S7Area.DB,
+            _ => throw new ArgumentOutOfRangeException(nameof(operand), operand, null)
+        };
+
+}