code: def test_label_html():
      """https://www.graphviz.org/doc/info/shapes.html#html"""
      dot = graphviz.Digraph(
          "structs", node_attr={"shape": "plaintext"}
      )
      dot.node(
          "struct1",
          """<
  <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
    <TR>
      <TD>left</TD>
      <TD PORT="f1">middle</TD>
      <TD PORT="f2">right</TD>
    </TR>
  </TABLE>>""",
      )
      dot.node(
          "struct2",
          """<
  <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
    <TR>
      <TD PORT="f0">one</TD>
      <TD>two</TD>
    </TR>
  </TABLE>>""",
      )
      dot.node(
          "struct3",
          """<
  <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0" CELLPADDING="4">
    <TR>
      <TD ROWSPAN="3">hello<BR/>world</TD>
      <TD COLSPAN="3">b</TD>
      <TD ROWSPAN="3">g</TD>
      <TD ROWSPAN="3">h</TD>
    </TR>
    <TR>
      <TD>c</TD>
      <TD PORT="here">d</TD>
      <TD>e</TD>
    </TR>
    <TR>
      <TD COLSPAN="3">f</TD>
    </TR>
  </TABLE>>""",
      )
      dot.edge("struct1:f1", "struct2:f0")
      dot.edge("struct1:f2", "struct3:here")
      assert (
          dot.source
          == """digraph structs {
  \tnode [shape=plaintext]
  \tstruct1 [label=<
  <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
    <TR>
      <TD>left</TD>
      <TD PORT="f1">middle</TD>
      <TD PORT="f2">right</TD>
    </TR>
  </TABLE>>]
  \tstruct2 [label=<
  <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
    <TR>
      <TD PORT="f0">one</TD>
      <TD>two</TD>
    </TR>
  </TABLE>>]
  \tstruct3 [label=<
  <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0" CELLPADDING="4">
    <TR>
      <TD ROWSPAN="3">hello<BR/>world</TD>
      <TD COLSPAN="3">b</TD>
      <TD ROWSPAN="3">g</TD>
      <TD ROWSPAN="3">h</TD>
    </TR>
    <TR>
      <TD>c</TD>
      <TD PORT="here">d</TD>
      <TD>e</TD>
    </TR>
    <TR>
      <TD COLSPAN="3">f</TD>
    </TR>
  </TABLE>>]
  \tstruct1:f1 -> struct2:f0
  \tstruct1:f2 -> struct3:here
  }
  """
      )
  
file_path: graphviz/tests/test_graphs.py
imports: import itertools
  import pytest
  import graphviz
label_desc: Use image node_id 17 for calling a global function with example usage: test_label_html() without return types