code: def test_scale_free_graph_negative_delta():
      with pytest.raises(ValueError, match="delta_in must be >= 0."):
          scale_free_graph(10, delta_in=-1)
      with pytest.raises(ValueError, match="delta_out must be >= 0."):
          scale_free_graph(10, delta_out=-1)
  
file_path: networkx/networkx/generators/tests/test_directed.py
imports: import pytest
  import networkx
  from networkx.classes import Graph, MultiDiGraph
  from networkx.generators.directed import gn_graph, gnc_graph, gnr_graph, random_k_out_graph, random_uniform_k_out_graph, scale_free_graph
label_desc: Use image node_id 1 for calling a global function with example usage: test_scale_free_graph_negative_delta() without return types