diff --git a/Slides/cell_manager.py b/Slides/cell_manager.py
index b3a4b9c..4b49204 100644
--- a/Slides/cell_manager.py
+++ b/Slides/cell_manager.py
@@ -1,134 +1,125 @@
 #!/bin/env python3
 
 import os
 import subprocess
 import shutil
 import nbformat
 ################################################################
 
 
 class NotFoundNotebooks(Exception):
-            "Could not find the notebooks to treat"
+    "Could not find the notebooks to treat"
 
 ################################################################
 
 
 def mergeNotebooks(notebook_files, add_cell_number=False, select_cells=None):
-
     "Merges several notebooks in a single one named: talk.ipynb"
     print("Merging notebooks {0}".format(notebook_files))
     notebooks = [nbformat.read(f, as_version=4) for f in notebook_files]
 
     if len(notebooks) == 0:
         raise NotFoundNotebooks
 
     cells = notebooks[0]['cells']
     for n in notebooks[1:]:
         cells += n['cells']
 
     if select_cells is None:
         select_cells = set(range(0, len(cells)))
 
     select_cells = set(select_cells)
 
     discard_cells = set(range(0, len(cells))) - select_cells
 
     new_cells = []
     for cell_number, c in enumerate(cells):
         if cell_number in discard_cells:
             continue
         # print(c)
         new_cells.append(c)
         if add_cell_number:
             new_cell = nbformat.notebooknode.NotebookNode()
             new_cell['cell_type'] = 'markdown'
             new_cell['source'] = 'Cell number {0}'.format(cell_number)
             new_cell['metadata'] = {}
             new_cells.append(new_cell)
         # print(new_cells)
     notebooks[0]['cells'] = new_cells
 
     nbformat.write(notebooks[0], 'talk.ipynb')
 
 ################################################################
 
 
 def launchSlideServer(options="", font_size="25px"):
-
     " Launch the HTTP server for reveal slides "
     dir_name = os.path.dirname(__file__)
     slides_config_file = os.path.join(dir_name, 'slides_config.py')
-    reveal_path = os.path.join(dir_name, '..', 'js', 'reveal.js')
+    # reveal_path = os.path.join(dir_name, '..', 'js', 'reveal.js')
     # cmd = ('jupyter nbconvert --to=Slides.myslides.SlidesExporter
     #         --config {1} --post serve '
     #        '--ServePostProcessor.open_in_browser=False'
     #        ' --reveal-prefix={0} {2} talk.ipynb').format(
     #                    reveal_path, slides_config_file, options)
     cmd = ('jupyter nbconvert --to=Slides.myslides.SlidesExporter '
-           '--config {1} --post serve --SlidesExporter.font_size={3} '
-           '--ServePostProcessor.open_in_browser=False'
-           ' {2} talk.ipynb').format(
-                       reveal_path, slides_config_file, options, font_size)
-
+           f'--config {slides_config_file} '
+           f'--post serve --SlidesExporter.font_size={font_size} '
+           '--ServePostProcessor.open_in_browser=False')
     print(cmd)
     subprocess.call(cmd, shell=True)
 
 ################################################################
 
 
 def generateHTML(options="", font_size="25px"):
-
     " Launch the HTTP server for reveal slides "
     dir_name = os.path.dirname(__file__)
     slides_config_file = os.path.join(dir_name, 'slides_config.py')
-    reveal_path = os.path.join(dir_name, 'js', './reveal.js')
-
+    # reveal_path = os.path.join(dir_name, 'js', './reveal.js')
     # cmd = ('jupyter nbconvert --to=Slides.myslides.SlidesExporter
     #          --config {1}'
     #        ' --reveal-prefix={0} {2} talk.ipynb').format(
     #                    reveal_path, slides_config_file, options)
 
     cmd = ('jupyter nbconvert --to=Slides.myslides.SlidesExporter '
-           '--config {1} --SlidesExporter.pdf_format="true" '
-           '--SlidesExporter.font_size={3}'
-           ' {2} talk.ipynb').format(
-                       reveal_path, slides_config_file, options, font_size)
+           f'--config {slides_config_file} --SlidesExporter.pdf_format="true" '
+           f'--SlidesExporter.font_size={font_size}'
+           f' {options} talk.ipynb')
 
     print(cmd)
     subprocess.call(cmd, shell=True)
 
 
 ################################################################
 
 
 def generateBeamer(options="", font_size="25px"):
-
     " Launch the HTTP server for reveal slides "
     dir_name = os.path.dirname(__file__)
     slides_config_file = os.path.join(dir_name, 'beamer_config.py')
-    reveal_path = os.path.join(dir_name, 'js', './reveal.js')
-
-    cmd = ('jupyter nbconvert --to=Slides.beamer.BeamerExporter --config {1} '
-           '--BeamerExporter.font_size={3}'
-           ' {2} talk.ipynb').format(
-                       reveal_path, slides_config_file, options, font_size)
+    # reveal_path = os.path.join(dir_name, 'js', './reveal.js')
+    cmd = (f'jupyter nbconvert --to=Slides.beamer.BeamerExporter '
+           f'--config {slides_config_file} '
+           f'--BeamerExporter.font_size={font_size}'
+           f' {options} talk.ipynb')
 
     print(cmd)
     subprocess.call(cmd, shell=True)
 
 
 ################################################################
 
 
 def executeNotebook(filename, options=""):
     " Request the execution of all cells "
     print('execute notebook: ', filename)
     dir_name = os.path.dirname(__file__)
     slides_config_file = os.path.join(dir_name, 'slides_execute_config.py')
     subprocess.call('jupyter nbconvert --to=notebook --output tmp.ipynb'
                     ' --config {0} {1}'.format(
-                                slides_config_file, filename), shell=True)
+                        slides_config_file, filename), shell=True)
     shutil.move('tmp.ipynb', filename)
     subprocess.call('jupyter trust {0}'.format(filename), shell=True)
 
 ################################################################