code: def test_with_prefix_default_category(
      dummies_with_unassigned, default_category, expected
  ):
      result = from_dummies(
          dummies_with_unassigned,
          sep="_",
          default_category=default_category,
      )
      expected = DataFrame(expected)
      tm.assert_frame_equal(result, expected)
  
imports: import numpy
  import pytest
  from pandas import DataFrame, Series, from_dummies, get_dummies
  import pandas._testing
label_desc: Use image node_id 30 for calling a global function with example usage: test_with_prefix_default_category(dummies_with_unassigned, default_category, expected) without return types