'Initialize the formatter with specified format strings.
Initialize the formatter either with the specified format string, or a
default as described above. Allow for specialized date formatting with
the optional datefmt argument (if omitted, you get the ISO8601 format).'

def __init__(self, fmt=None, datefmt=None):

    if fmt:
        self._fmt = fmt
    else:
        self._fmt = '%(message)s'
    self.datefmt = datefmt
