How to use the pygraphviz.agraph.AGraph function in pygraphviz

# checking filename and converting appropriately
		if filename == None:
			filename = 'computational_graph.png'

		if method != 'dot' and method != 'circo':
			method = 'dot'
		name, extension = filename.split('.')
		if extension != 'png' and extension != 'svg':
			print 'Only *.png or *.svg are supported formats!'
			print 'Using *.png now'
			extension = 'png'

		print 'name=',name, 'extension=', extension

		# setting the style for the nodes
		A = pygraphviz.agraph.AGraph(directed=True, strict = False)
		A.node_attr['fillcolor']="#000000"
		A.node_attr['shape']='rect'
		A.node_attr['width']='0.5'
		A.node_attr['height']='0.5'
		A.node_attr['fontcolor']='#ffffff'
		A.node_attr['style']='filled'
		A.node_attr['fixedsize']='true'

		# build graph
		for f in self.functionList:
			if f.type == 'var':
				A.add_node(f.id)
				continue
			for a in numpy.ravel(f.args):
				A.add_edge(a.id, f.id)
				#e = A.get_edge(a.source.id, f.id)

if orientation != 'LR' and orientation != 'TD' :
			orientation = 'TD'

		if method != 'dot' and method != 'circo':
			method = 'dot'
		name, extension = filename.split('.')
		if extension != 'png' and extension != 'svg':
			print 'Only *.png or *.svg are supported formats!'
			print 'Using *.png now'
			extension = 'png'

		print 'name=',name, 'extension=', extension

		# setting the style for the nodes
		A = pygraphviz.agraph.AGraph(directed=True, strict = False, rankdir = orientation)
		A.node_attr['fillcolor']= '#ffffff'
		A.node_attr['shape']='rect'
		A.node_attr['width']='0.5'
		A.node_attr['height']='0.5'
		A.node_attr['fontcolor']="#000000"
		A.node_attr['style']='filled'
		A.node_attr['fixedsize']='true'

		# build graph

		for f in self.functionList:
			if f.type == 'var' or f.type == 'const':
				A.add_node(f.id)
				continue
			for a in numpy.ravel(f.args):
				A.add_edge(a.id, f.id)

def intermediary_to_schema(tables, relationships, output):
    """ Transforms and save the intermediary representation to the file chosen. """
    from pygraphviz.agraph import AGraph
    dot_file = _intermediary_to_dot(tables, relationships)
    graph = AGraph()
    graph = graph.from_string(dot_file)
    extension = output.split('.')[-1]
    graph.draw(path=output, prog='dot', format=extension)

def intermediary_to_schema(tables, relationships, output):
    """ Transforms and save the intermediary representation to the file chosen. """
    dot_file = _intermediary_to_dot(tables, relationships)
    graph = AGraph()
    graph = graph.from_string(dot_file)
    extension = output.split('.')[-1]
    graph.draw(path=output, prog='dot', format=extension)

# checking filename and converting appropriately
        if filename is None:
            filename = 'computational_graph.png'

        if method != 'dot' and method != 'circo':
            method = 'dot'
        name, extension = filename.split('.')
        if extension != 'png' and extension != 'svg':
            print('Only *.png or *.svg are supported formats!')
            print('Using *.png now')
            extension = 'png'

        print('name=',name, 'extension=', extension)

        # setting the style for the nodes
        A = pygraphviz.agraph.AGraph(directed=True, strict = False)
        A.node_attr['fillcolor']="#000000"
        A.node_attr['shape']='rect'
        A.node_attr['width']='0.5'
        A.node_attr['height']='0.5'
        A.node_attr['fontcolor']='#ffffff'
        A.node_attr['style']='filled'
        A.node_attr['fixedsize']='true'

        # build graph
        for f in self.functionList:
            if f.type == 'var' or f.type=='const' or f.type=='id':
                A.add_node(f.id)
                continue
            for a in numpy.ravel(f.args):
                A.add_edge(a.id, f.id)
                #e = A.get_edge(a.source.id, f.id)

if orientation != 'LR' and orientation != 'TD' :
            orientation = 'TD'

        if method != 'dot' and method != 'circo':
            method = 'dot'
        name, extension = filename.split('.')
        if extension != 'png' and extension != 'svg':
            print 'Only *.png or *.svg are supported formats!'
            print 'Using *.png now'
            extension = 'png'

        print 'name=',name, 'extension=', extension

        # setting the style for the nodes
        A = pygraphviz.agraph.AGraph(directed=True, strict = False, rankdir = orientation)
        A.node_attr['fillcolor']= '#ffffff'
        A.node_attr['shape']='rect'
        A.node_attr['width']='0.5'
        A.node_attr['height']='0.5'
        A.node_attr['fontcolor']="#000000"
        A.node_attr['style']='filled'
        A.node_attr['fixedsize']='true'

        # build graph

        for f in self.functionList:
            if f.type == 'var' or f.type == 'const':
                A.add_node(f.id)
                continue
            for a in numpy.ravel(f.args):
                A.add_edge(a.id, f.id)

"""
    Plots a graph in graphviz dot notation.

    :param graph: the dot notation graph
    :type graph: str
    :param filename: the (optional) file to save the generated plot to. The extension determines the file format.
    :type filename: str
    """
    if not plot.pygraphviz_available:
        logger.error("Pygraphviz is not installed, cannot generate graph plot!")
        return
    if not plot.PIL_available:
        logger.error("PIL is not installed, cannot display graph plot!")
        return

    agraph = AGraph(graph)
    agraph.layout(prog='dot')
    if filename is None:
        filename = tempfile.mktemp(suffix=".png")
    agraph.draw(filename)
    image = Image.open(filename)
    image.show()

def to_directed(self, **kwds):
        """Return directed copy of graph.

        Each undirected edge u-v is represented as two directed
        edges u->v and v->u.
        """
        if not self.directed:
            D = AGraph(strict=self.strict, directed=True)
            D.graph_attr.update(self.graph_attr)
            D.node_attr.update(self.node_attr)
            D.edge_attr.update(self.edge_attr)
            for n in self.nodes():
                D.add_node(n)
                new_n = Node(D, n)
                new_n.attr.update(n.attr)
            for e in self.edges():
                (u, v) = e
                D.add_edge(u, v)
                D.add_edge(v, u)
                uv = D.get_edge(u, v)
                vu = D.get_edge(v, u)
                uv.attr.update(e.attr)
                uv.attr.update(e.attr)
                vu.attr.update(e.attr)