Add example to code doc

server/lib/python/cartodb_services/cartodb_services/mapzen/matrix_client.py

@@ -3,6 +3,18 @@ import json
 
 class MatrixClient:
 
+    """
+    A minimal client for Mapzen Time-Distance Matrix Service
+
+    Example:
+
+    client = MatrixClient('your_api_key')
+    locations = [{"lat":40.744014,"lon":-73.990508},{"lat":40.739735,"lon":-73.979713},{"lat":40.752522,"lon":-73.985015},{"lat":40.750117,"lon":-73.983704},{"lat":40.750552,"lon":-73.993519}]
+    costing = 'pedestrian'
+
+    print client.one_to_many(locations, costing)
+    """
+
     ONE_TO_MANY_URL = 'https://matrix.mapzen.com/one_to_many'
 
     def __init__(self, matrix_key):