Update simple.py

Author: lzchen

contrib/opencensus-ext-azure/examples/metrics/simple.py

@@ -12,8 +12,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import time
-
 from opencensus.ext.azure import metrics_exporter
 from opencensus.stats import aggregation as aggregation_module
 from opencensus.stats import measure as measure_module