Update pyfile.py

Author: ReikaNekoUwU

pyfoxfile/pyfile.py

@@ -115,6 +115,12 @@ def get_importing_script_path():
             return os.path.abspath(filename)
     return None
 
+def is_only_nonprintable(var):
+    """True if every character is non-printable (handles bytes via to_text)."""
+    if var is None:
+        return True
+    return all(not ch.isprintable() for ch in var)
+
 def add_format(reg, key, magic, ext, name=None, ver="001",
                new_style=True, use_advanced_list=True, use_alt_inode=False, delim="\x00"):
     if key in reg: