code: def test_unequal_start_end_bounds():
      class CustomIndexer(BaseIndexer):
          def get_window_bounds(
              self, num_values, min_periods, center, closed, step
          ):
              return np.array([1]), np.array([1, 2])
  
      indexer = CustomIndexer()
      roll = Series(1).rolling(indexer)
      match = "start"
      with pytest.raises(ValueError, match=match):
          roll.mean()
  
      with pytest.raises(ValueError, match=match):
          next(iter(roll))
  
      with pytest.raises(ValueError, match=match):
          roll.corr(pairwise=True)
  
      with pytest.raises(ValueError, match=match):
          roll.cov(pairwise=True)
  
imports: import numpy
  import pytest
  from pandas import DataFrame, MultiIndex, Series, concat, date_range
  import pandas._testing
  from pandas.api.indexers import BaseIndexer, FixedForwardWindowIndexer
  from pandas.core.indexers.objects import ExpandingIndexer, FixedWindowIndexer, VariableOffsetWindowIndexer
  from pandas.tseries.offsets import BusinessDay
label_desc: Use image node_id 17 for calling a global function with example usage: test_unequal_start_end_bounds() and returns: np,  np