code: def test_ewm_alpha_arg(series):
      # GH 10789
      s = series
      msg = "Must pass one of comass, span, halflife, or alpha"
      with pytest.raises(ValueError, match=msg):
          s.ewm()
  
      msg = "comass, span, halflife, and alpha are mutually exclusive"
      with pytest.raises(ValueError, match=msg):
          s.ewm(com=10.0, alpha=0.5)
      with pytest.raises(ValueError, match=msg):
          s.ewm(span=10.0, alpha=0.5)
      with pytest.raises(ValueError, match=msg):
          s.ewm(halflife=10.0, alpha=0.5)
  
imports: import numpy
  import pytest
  from pandas import DataFrame, DatetimeIndex, Series, date_range
  import pandas._testing
label_desc: Use image node_id 32 for calling a global function with example usage: test_ewm_alpha_arg(series) without return types