DOC: give usage example

doc/developers/utilities.rst

@@ -270,7 +270,14 @@ Hash Functions
   `MurmurHash3_x86_32` C++ non cryptographic hash function. This hash
   function is suitable for implementing lookup tables, Bloom filters,
   Count Min Sketch, feature hashing and implicitly defined sparse
-  random projections.
+  random projections::
+
+    >>> from sklearn.utils import murmurhash3_32
+    >>> murmurhash3_32("some feature", seed=0)
+    -384616559
+
+    >>> murmurhash3_32("some feature", seed=0, positive=True)
+    3910350737L
 
   The ``sklearn.utils.murmurhash`` module can also be "cimported" from
   other cython modules so as to benefit from the high performance of