def _check_file_existence(self, files):
for f in files:<EOL><INDENT>if not os.path.isfile(f):<EOL><INDENT>logging.error("<STR_LIT>" % f)<EOL>exit(<NUM_LIT:1>)<EOL><DEDENT><DEDENT>
Iterate through files and exit(1) if any do not pass
        os.path.isfile