Document Sensor.value function

Fixes #133

Author: ddemidov

ev3dev/core.py

@@ -1341,6 +1341,12 @@ def units(self):
 # ~autogen
 
     def value(self, n=0):
+        """
+        Returns the value or values measured by the sensor. Check num_values to
+        see how many values there are. Values with N >= num_values will return
+        an error. The values are fixed point numbers, so check decimals to see
+        if you need to divide to get the actual value.
+        """
         if isinstance(n, numbers.Integral):
             n = '{0:d}'.format(n)
         elif isinstance(n, numbers.Real):