TypeError: 'SumAggregation' object is not callable

[howardyoo]

Environment
Python 3.9.9 on MacOS Monterey (version 12.2.1) on M1 Arm Architecture

Steps to reproduce

• clone and install opentelemetry-python repo
• run the following pip installation

pip install -e ./opentelemetry-sdk
pip install -e ./opentelemetry-api

Run the following test code to test opentelemetry's metric (simple counter)

from re import I
import time
from opentelemetry._metrics import get_meter_provider, set_meter_provider
from opentelemetry.sdk._metrics.export import ConsoleMetricExporter
from opentelemetry.exporter.otlp.proto.grpc._metric_exporter import (
    OTLPMetricExporter,
)
from opentelemetry.sdk._metrics import MeterProvider
from opentelemetry.sdk._metrics.export import PeriodicExportingMetricReader

exporter = ConsoleMetricExporter()

print("setting up metric reader..")
reader = PeriodicExportingMetricReader(exporter=exporter, export_interval_millis=1000)
provider = MeterProvider(metric_readers=[reader])

print("setting meter provider..")
set_meter_provider(provider)

print("getting meter provider..")
# meter = get_meter_provider().get_meter("getting-started")
meter = provider.get_meter("howard")
print(meter)

print("creating counter..")
counter = meter.create_counter("first_counter")
print("adding 1")
counter.add(1)

time.sleep(3)
print("adding 5")
counter.add(5)

time.sleep(5)
print("adding 5")
counter.add(5)

What is the expected behavior?
Expected to see a successful list of metrics being emitted into the console.

What is the actual behavior?
I saw the following error in my script:

setting up metric reader..
setting meter provider..
getting meter provider..
<opentelemetry.sdk._metrics.Meter object at 0x105b192b0>
creating counter..
adding 1
Traceback (most recent call last):
  File "/Users/howardyoo/python/otel/otelmetric.py", line 30, in <module>
    counter.add(1)
  File "/Users/howardyoo/git/opentelemetry-python/opentelemetry-sdk/src/opentelemetry/sdk/_metrics/instrument.py", line 97, in add
    self._measurement_consumer.consume_measurement(
  File "/Users/howardyoo/git/opentelemetry-python/opentelemetry-sdk/src/opentelemetry/sdk/_metrics/measurement_consumer.py", line 61, in consume_measurement
    reader_storage.consume_measurement(measurement)
  File "/Users/howardyoo/git/opentelemetry-python/opentelemetry-sdk/src/opentelemetry/sdk/_metrics/metric_reader_storage.py", line 101, in consume_measurement
    matches.consume_measurement(measurement)
  File "/Users/howardyoo/git/opentelemetry-python/opentelemetry-sdk/src/opentelemetry/sdk/_metrics/_view_instrument_match.py", line 71, in consume_measurement
    self._attributes_aggregation[attributes] = self._aggregation()
TypeError: 'SumAggregation' object is not callable

Additional context
Looks like the line 71 in _view_instrument_match.py had an incorrect '()' at the end of the object's assignment - since the object is not a function, the TypeError: 'SumAggregation' object is not callable was resulted.