code: def open(self, function_context):
      mg = function_context.get_metric_group()
      self.counter = mg.add_group("key", "value").counter("my_counter")
      self.counter_sum = 0
  
imports: import uuid
  from pyflink.table.expressions import col, call, lit, row_interval
  from pyflink.table.types import DataTypes
  from pyflink.table.udf import udaf, udf, AggregateFunction
  from pyflink.testing import source_sink_utils
  from pyflink.testing.test_case_utils import PyFlinkBatchTableTestCase, PyFlinkStreamTableTestCase
label_desc: Use image node_id 2 for calling the MaxAdd obj's underlying member method code with example usage: obj.open(function_context) without return types