diff --git a/doc/source/images/generate_io_overview.py b/doc/source/images/generate_io_overview.py
index 8cc2832881..adf1573811 100644
--- a/doc/source/images/generate_io_overview.py
+++ b/doc/source/images/generate_io_overview.py
@@ -9,6 +9,7 @@
 
 import pygraphviz
 import neo
+
 # from datetime import datetime
 #
 # import numpy as np
@@ -45,12 +46,14 @@
 styles['ext']['shape'] = 'circle'
 styles['ext']['fillcolor'] = 'red'
 styles['ext']['style'] = 'filled'
+
+
 # styles['ext']['fixedsize'] = 'True'
 
 
 def generate_diagram(filename, plot_extensions=False):
     dia = pygraphviz.AGraph(strict=False, splines='true')
-    G=dia
+    G = dia
     G.node_attr['fontname'] = 'Arial'
     # G.node_attr['shape'] = 'circle'
     # G.node_attr['fixedsize'] = 'true'
@@ -68,7 +71,6 @@ def generate_diagram(filename, plot_extensions=False):
     G.graph_attr['ratio'] = '1.0'
     # G.edge_attr['color'] = '#1100FF'
 
-
     G.edge_attr['style'] = 'setlinewidth(4)'
 
     dia.add_node('NEO', shape='circle', fontsize=50)
@@ -103,13 +105,12 @@ def generate_diagram(filename, plot_extensions=False):
                 dia.add_node(ext, **styles['ext'])
                 dia.add_edge(io_name, ext, minlen=0)
 
-    dia.layout(prog='fdp') #neato, dot, twopi, circo, fdp, nop, wc, acyclic, gvpr, gvcolor,
+    dia.layout(prog='fdp')  # neato, dot, twopi, circo, fdp, nop, wc, acyclic, gvpr, gvcolor,
     # ccomps, sccmap, tred, sfdp.
     for ext in ['png', 'svg', 'eps']:
         dia.draw('{}.{}'.format(filename, ext))
 
 
-
 if __name__ == '__main__':
     generate_diagram('IODiagram', plot_extensions=False)
     generate_diagram('IODiagram_ext', plot_extensions=True)