diff --git a/README.rst b/README.rst
index 6d972f2..5822bd9 100644
--- a/README.rst
+++ b/README.rst
@@ -92,20 +92,24 @@ For humidity compensated raw gas and voc index readings, we'll need a secondary
         humidity = bme280.relative_humidity
 
         # For compensated raw gas readings
-        compensated_raw_gas = sgp.measure_raw(temperature = temperature, relative_humidity = humidity)
-
-        time.sleep(1)
+        """
+        compensated_raw_gas = sgp.measure_raw(
+            temperature=temperature, relative_humidity=humidity
+        )
+        print("Raw Data:", compensated_raw_gas)
+        """
 
         # For Compensated voc index readings
-        voc_index = sgp.measure_index(temperature = temperature, relative_humidity = humidity)
+        voc_index = sgp.measure_index(
+        temperature=temperature, relative_humidity=humidity)
 
-        print(compensated_raw_gas)
-        print(voc_index)
+        print("VOC Index:", voc_index)
         print("")
         time.sleep(1)
 
-
 It may take several minutes for the VOC index to start changing as it calibrates the baseline readings.
+The voc algorithm expects a 1 hertz sampling rate. Run `measure_index()` once per second.
+
 
 Contributing
 ============
diff --git a/adafruit_sgp40/voc_algorithm.py b/adafruit_sgp40/voc_algorithm.py
index 3106fa2..dfc8e73 100644
--- a/adafruit_sgp40/voc_algorithm.py
+++ b/adafruit_sgp40/voc_algorithm.py
@@ -11,6 +11,7 @@
 * Author(s): yangfeng
 
 """
+from micropython import const
 
 _VOCALGORITHM_SAMPLING_INTERVAL = const(1)
 _VOCALGORITHM_INITIAL_BLACKOUT = const(45)
diff --git a/examples/sgp40_indextest.py b/examples/sgp40_indextest.py
index 5d9dd4d..cef744e 100644
--- a/examples/sgp40_indextest.py
+++ b/examples/sgp40_indextest.py
@@ -18,18 +18,19 @@
     humidity = bme280.relative_humidity
 
     # For compensated raw gas readings
+    """
     compensated_raw_gas = sgp.measure_raw(
         temperature=temperature, relative_humidity=humidity
     )
-
-    time.sleep(1)
+    print("Raw Data:", compensated_raw_gas)
+    """
 
     # For Compensated voc index readings
+    # The algorithm expects a 1 hertz sampling rate. Run "measure index" once per second.
     # It may take several minutes for the VOC index to start changing
     # as it calibrates the baseline readings.
     voc_index = sgp.measure_index(temperature=temperature, relative_humidity=humidity)
 
-    print("Raw Data:", compensated_raw_gas)
     print("VOC Index:", voc_index)
     print("")
     time.sleep(1)