Index: gc_lang/fr/build.py
==================================================================
--- gc_lang/fr/build.py
+++ gc_lang/fr/build.py
@@ -22,11 +22,11 @@
     dir_util.copy_tree("gc_lang/"+sLang+"/webext/", "_build/webext/"+sLang)
     dir_util.copy_tree("grammalecte-js", "_build/webext/"+sLang+"/grammalecte")
     dVars['webextOptionsHTML'] = _createOptionsForWebExtension(dVars)
     helpers.copyAndFileTemplate("_build/webext/"+sLang+"/manifest.json", "_build/webext/"+sLang+"/manifest.json", dVars)
     helpers.copyAndFileTemplate("_build/webext/"+sLang+"/panel/main.html", "_build/webext/"+sLang+"/panel/main.html", dVars)
-    with helpers.cd("_build/webext/"+sLang):
+    with helpers.CD("_build/webext/"+sLang):
         os.system("web-ext build")
 
 
 def _createOptionsForWebExtension (dVars):
     sHTML = ""

Index: helpers.py
==================================================================
--- helpers.py
+++ helpers.py
@@ -1,16 +1,18 @@
-# Useful tools
+"""
+Tools for handling files
+"""
 
 import os
 import shutil
 import errno
 import zipfile
 
 from string import Template
 
 
-class cd:
+class CD:
     "Context manager for changing the current working directory"
     def __init__ (self, newPath):
         self.newPath = os.path.expanduser(newPath)
         self.savedPath = ""
 
@@ -59,10 +61,11 @@
     else:
         eraseFolder(sp)
 
 
 def copyFolderContent (spSrc, spDst):
+    "copy folder content from src to dst"
     try:
         shutil.copytree(spSrc, spDst)
     except OSError as e:
         if e.errno == errno.ENOTDIR:
             shutil.copy(spSrc, spDst)
@@ -80,10 +83,11 @@
     s = Template(open(spfSrc, "r", encoding="utf-8").read()).safe_substitute(dVars)
     open(spfDst, "w", encoding="utf-8", newline="\n").write(s)
 
 
 def addFolderToZipAndFileFile (hZip, spSrc, spDst, dVars, bRecursive):
+    "add folder content to zip archive and file files with <dVars>"
     # recursive function
     spSrc = spSrc.strip("/ ")
     spDst = spDst.strip("/ ")
     for sf in os.listdir(spSrc):
         spfSrc = (spSrc + "/" + sf).strip("/ ")
@@ -91,10 +95,8 @@
         if os.path.isdir(spfSrc):
             if bRecursive:
                 addFolderToZipAndFileFile(hZip, spfSrc, spfDst, dVars, bRecursive)
         else:
             if spfSrc.endswith((".py", ".js", ".css", ".xcu", ".xul", ".rdf", ".dtd", ".properties")):
-                #print(spfSrc + " > " + spfDst)
                 hZip.writestr(spfDst, fileFile(spfSrc, dVars))
             else:
-                #print(spfSrc + " > " + spfDst)
                 hZip.write(spfSrc, spfDst)

Index: make.py
==================================================================
--- make.py
+++ make.py
@@ -451,16 +451,16 @@
                         hDst = open("./gc_lang/"+sLang+"/perf_memo.txt", "a", encoding="utf-8", newline="\n")  if xArgs.perf_memo  else None
                         tests.perf(sVersion, hDst)
 
             # Firefox (obsolete)
             #if False:
-            #    with helpers.cd("_build/xpi/"+sLang):
+            #    with helpers.CD("_build/xpi/"+sLang):
             #        spfFirefox = dVars['win_fx_dev_path']  if platform.system() == "Windows"  else dVars['linux_fx_dev_path']
             #        os.system('jpm run -b "' + spfFirefox + '"')
 
             if xArgs.web_ext or xArgs.firefox:
-                with helpers.cd("_build/webext/"+sLang):
+                with helpers.CD("_build/webext/"+sLang):
                     if xArgs.lint_web_ext:
                         os.system(r'web-ext lint -o text')
                     if xArgs.firefox:
                         # Firefox Developper edition
                         spfFirefox = dVars['win_fx_dev_path']  if platform.system() == "Windows"  else dVars['linux_fx_dev_path']