added lagged value functionality for retrieving values further down in memory; Converted position always to lower case strings to avoid problems with caps sensitivity names; added examples for use in examples.js

src/measurements/MeasurementContainer.js

@@ -94,7 +94,8 @@ class MeasurementContainer {
       throw new Error('Variant must be specified before position');
     }
 
-    this._currentPosition = positionValue;
+    
+    this._currentPosition = positionValue.toString().toLowerCase();;
     
     return this;
   }
@@ -247,9 +248,31 @@ class MeasurementContainer {
     return measurement ? measurement.getAllValues() : null;
   }
 
+  getLaggedValue(lag = 1,requestedUnit = null ){
+    const measurement = this.get();
+    if (!measurement) return null;
+    
+    const value = measurement.getLaggedSample(lag);
+    if (value === null) return null;
 
-  differenceUpDown(){
+    // Return as-is if no unit conversion requested
+    if (!requestedUnit) {
+      return value;
+    }
 
+    // Convert if needed
+    if (measurement.unit && requestedUnit !== measurement.unit) {
+      try {
+        return convertModule(value).from(measurement.unit).to(requestedUnit);
+      } catch (error) {
+        if (this.logger) {
+          this.logger.error(`Unit conversion failed: ${error.message}`);
+        }
+        return value; // Return original value if conversion fails
+      }
+    }
+
+    return value;
   }