human
Complete the below
def draw_graphviz(tree, label_func=str, prog='twopi', args='', node_color='#c0deff', **kwargs):

    ''''Display a tree or clade as a graph, using the graphviz engine.
    Requires NetworkX, matplotlib, Graphviz and either PyGraphviz or pydot.
    The third and fourth parameters apply to Graphviz, and the remaining
    arbitrary keyword arguments are passed directly to networkx.draw(), which
    in turn mostly wraps matplotlib/pylab.  See the documentation for Graphviz
    and networkx for detailed explanations.
    The NetworkX/matplotlib parameters are described in the docstrings for
    networkx.draw() and pylab.scatter(), but the most reasonable options to try
    are: *alpha, node_color, node_size, node_shape, edge_color, style,
    font_size, font_color, font_weight, font_family*
    :Parameters:
    label_func : callable
    A function to extract a label from a node. By default this is str(),
    but you can use a different function to select another string
    associated with each node. If this function returns None for a node,
    no label will be shown for that node.
    The label will also be silently skipped if the throws an exception
    related to ordinary attribute access (LookupError, AttributeError,
    ValueError).
all other exception types will still be raised. This
    means you can use a lambda expression that simply attempts to look
    up the desired value without checking if the intermediate attributes
    are available:
    >>> Phylo.draw_graphviz(tree, lambda n: n.taxonomies[0].code)
    prog : string
    The Graphviz program to use when rendering the graph. \'twopi\'
    behaves the best for large graphs, reliably avoiding crossing edges,
    but for moderate graphs \'neato\' looks a bit nicer.  For small
    directed graphs, \'dot\' may produce a normal-looking cladogram, but
    will cross and distort edges in larger graphs. (The programs \'circo\'
    and \'fdp\' are not recommended.)
    args : string
    Options passed to the external graphviz program.  Normally not
    needed, but offered here for completeness.
    Example
    >>> import pylab
    >>> from Bio import Phylo
   ...'''
assistant
#Here is the Python code you requested.
    import warnings
    from Bio import BiopythonDeprecationWarning
    warnings.warn('draw_graphviz    is    deprecated;    use    Bio.Phylo.draw    instead', BiopythonDeprecationWarning)
    try:
        import networkx
    except ImportError:
        raise MissingPythonDependencyError('Install    NetworkX    if    you    want    to    use    to_networkx.')
    G = to_networkx(tree)
    try:
        Gi = networkx.convert_node_labels_to_integers(G, label_attribute='label')
        int_labels = {}
        for (integer, nodeattrs) in Gi.node.items():
            int_labels[nodeattrs['label']] = integer
    except TypeError:
        Gi = networkx.convert_node_labels_to_integers(G, discard_old_labels=False)
        int_labels = Gi.node_labels
    try:
        if hasattr(networkx, 'graphviz_layout'):
            graphviz_layout = networkx.graphviz_layout
        else:
            graphviz_layout = networkx.drawing.nx_agraph.graphviz_layout
        posi = graphviz_layout(Gi, prog, args=args)
    except ImportError:
        raise MissingPythonDependencyError('Install    PyGraphviz    or    pydot    if    you    want    to    use    draw_graphviz.')
    def get_label_mapping(G, selection):
        'Apply    the    user-specified    node    relabeling.'
        for node in G.nodes():
            if ((selection is None) or (node in selection)):
                try:
                    label = label_func(node)
                    if (label not in (None, node.__class__.__name__)):
                        (yield (node, label))
                except (LookupError, AttributeError, ValueError):
                    pass
    if ('nodelist' in kwargs):
        labels = dict(get_label_mapping(G, set(kwargs['nodelist'])))
    else:
        labels = dict(get_label_mapping(G, None))
    kwargs['nodelist'] = list(labels.keys())
    if ('edge_color' not in kwargs):
        kwargs['edge_color'] = [((isinstance(e[2], dict) and e[2].get('color', 'k')) or 'k') for e in G.edges(data=True)]
    if ('width' not in kwargs):
       ...