code: def test_as_series():
      assert isinstance(as_series([1, 2, 3]), pd.Series)
      assert isinstance(as_series(np.arange(5)), pd.Series)
      assert isinstance(as_series(pd.Series([1, 2, 3])), pd.Series)
  
imports: from pmdarima.utils.array import diff, diff_inv, c, is_iterable, as_series, check_exog, check_endog
  from pmdarima.utils import get_callable
  from numpy.testing import assert_array_equal, assert_array_almost_equal
  import datetime
  import pytest
  import pandas
  import numpy
label_desc: Use image node_id 9 for calling a global function with example usage: test_as_series() without return types