class_docstr: Unit tests for writing a graph to a file in graph6 format.
class_docstr_tok: ["Unit","tests","for","writing","a","graph","to","a","file","in","graph6","format","."]
code: def test_no_directed_or_multi_graphs(self, G):
      with pytest.raises(nx.NetworkXNotImplemented):
          nx.write_graph6(G, BytesIO())
  
imports: from io import BytesIO
  import pytest
  import networkx
  import networkx.readwrite.graph6
  from networkx.utils import edges_equal, nodes_equal
label_desc: Use image node_id 7 for calling the TestWriteGraph6 obj's underlying member method code with example usage: obj.test_no_directed_or_multi_graphs(G) without return types