code: def test_ewm_mean():
      array = [1, np.nan, 3, 4, 5, 6, np.nan, 7]
  
      s = Stream.source(array, dtype="float")
  
      for config in configurations:
          w = s.ewm(**config).mean().rename("w")
          expected = list(pd.Series(array).ewm(**config).mean())
  
          assert_op([w], expected)
  
imports: import numpy
  import pandas
  from tensortrade.feed import Stream
  from tests.utils.ops import assert_op
label_desc: Use image node_id 1 for calling a global function with example usage: test_ewm_mean() without return types