def walkfiles(folder, suffix=''):
 return (os.path.join(basename, filename) for (basename, dirnames, filenames) in os.walk(folder) for filename in filenames if filename.endswith(suffix))

def walkfiles ( folder , suffix = '' ) : return ( os . path . join ( basename , filename ) for ( basename , dirnames , filenames ) in os . walk ( folder ) for filename in filenames if filename . endswith ( suffix ) )
iterator over files in folder .