code: def test_invalid_signatures(self, sigs):
      def default(x, y):
          return x + y
  
      with pytest.raises(ValueError):
          _GUFunc(default, "(i),(i)->(i)", signatures=sigs)
  
imports: import numpy
  import pytest
  import cupy
  from cupy import testing
  from cupy._core._gufuncs import _GUFunc
label_desc: Use image node_id 3 for calling the TestGUFuncSignatures obj's underlying member method code with example usage: obj.test_invalid_signatures(sigs) and returns: unknown