Merge pull request #952 from Mathics3/fix-range

Add description for Range

mathics/builtin/list/constructing.py

@@ -212,7 +212,13 @@ class Range(Builtin):
       <dd>returns a list of integers from 1 to $n$.
 
       <dt>'Range[$a$, $b$]'
-      <dd>returns a list of integers from $a$ to $b$.
+      <dd>returns a list of (Integer, Rational, Real) numbers from $a$ to $b$.
+
+      <dt>'Range[$a$, $b$, $di$]'
+      <dd>returns a list of numbers from $a$ to $b$ using step $di$.
+        More specifically, 'Range' starts from $a$ and successively adds \
+        increments of $di$ until the result is greater (if $di$ > 0) or \
+        less (if $di$ < 0) than $b$.
     </dl>
 
     >> Range[5]