code: def mean_udaf(v):
      return v.mean()
  
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 a global function with example usage: mean_udaf(v) and returns: v