human
Complete the below
def dotprint(expr, styles=default_styles, atom=(lambda x: (not isinstance(x, Basic))), maxdepth=None, repeat=True, labelfunc=str, **kwargs):

    ''''DOT description of a SymPy expression tree
    Options are
    ``styles``: Styles for different classes.  The default is::
    [(Basic, {\'color\': \'blue\', \'shape\': \'ellipse\'}),
    (Expr, {\'color\': \'black\'})]``
    ``atom``: Function used to determine if an arg is an atom.  The default is
    ``lambda x: not isinstance(x, Basic)``.  Another good choice is
    ``lambda x: not x.args``.
    ``maxdepth``: The maximum depth.  The default is None, meaning no limit.
    ``repeat``: Whether to different nodes for separate common subexpressions.
    The default is True.  For example, for ``x + x*y`` with
    ``repeat=True``, it will have two nodes for ``x`` and with
    ``repeat=False``, it will have one (warning: even if it appears
    twice in the same object, like Pow(x, x), it will still only appear
    only once.  Hence, with repeat=False, the number of arrows out of an
    object might not equal the number of args it has).
    ``labelfunc``: How to label leaf nodes.  The default is ``str``.  Another
    good option is ``srepr``. For example with ``str``, the leaf nodes
    of ``x + 1`` are labeled, ``x`` and ``1``.  With ``srepr``, they
    are labeled ``Symbol(\'x\')`` and ``Integer(1)``.
    Additional keyword arguments are included as styles for the graph.
    Examples
    >>> from sympy.printing.dot import dotprint
    >>> from sympy.abc import x
    >>> print(dotprint(x+2)) # doctest: +NORMALIZE_WHITESPACE
    digraph{
    <BLANKLINE>
    # Graph style
    "ordering"="out"
    "rankdir"="TD"
    <BLANKLINE>
    # Nodes #
    <BLANKLINE>
    "Add(Integer(2), Symbol(x))_()" ["color"="black", "label"="Add", "shape"="ellipse"];
    "Integer(2)_(0,)" ["color"="black", "label"="2", "shape"="ellipse"];
    "Symbol(x)_(1,)" ["color"="black", "label"="x", "shape"="ellipse"];
    <BLANKLINE>
    # Edges #
    <BLANKLINE>
    "Add(Integer(2), Symbol(x))_()" -> "Integer(2)_(0,)";
    "Add(Integer(2), Symbol(x))_()" -> "Symbol(x)_(1,)";'
    '''

=====
What is a Python program to determine if an arg is an atom?
assistant
#Here is Python program to determine if an arg is an atom.
    graphstyle.update(kwargs)
    nodes = []
    edges = []
    def traverse(e, depth, pos=()):
        nodes.append(dotnode(e, styles, labelfunc=labelfunc, pos=pos, repeat=repeat))
        if (maxdepth and (depth >= maxdepth)):
            return
        edges.extend(dotedges(e, atom=atom, pos=pos, repeat=repeat))
        [traverse(arg, (depth + 1), (pos + (i,))) for (i, arg) in enumerate(e.args) if (not atom(arg))]
    traverse(expr, 0)
    return (template % {'graphstyle': attrprint(graphstyle, delimiter='\n'), 'nodes': '\n'.join(nodes), 'edges': '\n'.join(edges)})