Minor fixes

src/snipper/snipper_main.py

@@ -7,6 +7,7 @@ from snipper.fix_s import save_s
 from snipper.fix_cite import fix_citations
 from snipper.fix_bf import fix_f, fix_b
 from snipper.fix_o import run_o
+from sphinx.ext.autodoc.preserve_defaults import update_defvalue
 
 
 def rem_nonprintable_ctrl_chars(txt):
@@ -46,10 +47,15 @@ def censor_file(file, run_files=True, run_out_dirs=None, cut_files=True,
                 strict=True,
                 references=None,
                 license_head=None,
-                package_base_dir=None):
+                package_base_dir=None,
+                update_file=True # Update the file 'file' (i.e., write to it).
+                ):
     if str(file).endswith("rst"):
         assert not run_files and not cut_files and not censor_files
 
+    if censor_files:
+        assert update_file, "update_file must be true when censor_files is true (otherwise the file will not be censored!)"
+
     if str(file).endswith(".md"):
         license_head=None
 
@@ -108,6 +114,7 @@ def censor_file(file, run_files=True, run_out_dirs=None, cut_files=True,
     if license_head is not None:
         s2 = fix_copyright(s2, license_head)
 
+    if update_file:
         with open(file, 'w', encoding='utf-8') as f:
             f.write(s2)
     return nB, cut