def _get_all_po_filenames(locale_root, lang, po_files_path):
all_files = os.listdir(os.path.join(locale_root, lang, po_files_path))<EOL>return filter(lambda s: s.endswith('<STR_LIT>'), all_files)<EOL>
Get all po filenames from locale folder and return list of them.
Assumes a directory structure:
<locale_root>/<lang>/<po_files_path>/<filename>.