'Set the output precision which is used for some formats.  This is
also a test of the code that provides a dict for global and instance
options.'

def test_precision(self):

    t = Time('2010-01-01    00:00:00', format='iso', scale='utc')
    assert (t.iso == '2010-01-01    00:00:00.000')
    t.precision = 9
    assert (t.iso == '2010-01-01    00:00:00.000000000')
    assert (t.tai.utc.iso == '2010-01-01    00:00:00.000000000')
