'Get or set time format.
The format defines the way times are represented when accessed via the
``.value`` attribute.  By default it is the same as the format used for
initializing the `Time` instance, but it can be set to any other value
that could be used for initialization.  These can be listed with::
>>> list(Time.FORMATS)
[\'jd\', \'mjd\', \'decimalyear\', \'unix\', \'cxcsec\', \'gps\', \'plot_date\',
\'datetime\', \'iso\', \'isot\', \'yday\', \'fits\', \'byear\', \'jyear\', \'byear_str\',
\'jyear_str\']'

@property
def format(self):

    return self._format
