def start_file_logger(filename, name='<STR_LIT>', level=logging.DEBUG, format_string=None):
if format_string is None:<EOL><INDENT>format_string = "<STR_LIT>"<EOL><DEDENT>global logger<EOL>logger = logging.getLogger(name)<EOL>logger.setLevel(level)<EOL>handler = logging.FileHandler(filename)<EOL>handler.setLevel(level)<EOL>formatter = logging.Formatter(format_string, datefmt='<STR_LIT>')<EOL>handler.setFormatter(formatter)<EOL>logger.addHandler(handler)<EOL>
Add a stream log handler.

    Parameters
    ---------

    filename: string
        Name of the file to write logs to. Required.
    name: string
        Logger name. Default="parsl.executors.interchange"
    level: logging.LEVEL
        Set the logging level. Default=logging.DEBUG
        - format_string (string): Set the format string
    format_string: string
        Format string to use.

    Returns
    -------
        None.