code: def test_er(self):
      result = pandas_ta.er(self.close)
      self.assertIsInstance(result, Series)
      self.assertEqual(result.name, "ER_10")
  
imports: from .config import error_analysis, sample_data, CORRELATION, CORRELATION_THRESHOLD, VERBOSE
  from .context import pandas_ta
  from unittest import TestCase, skip
  import pandas.testing
  from pandas import DataFrame, Series
  import talib
label_desc: Use image node_id 18 for calling the TestMomentum obj's underlying member method code with example usage: obj.test_er() without return types