How to use the grafanalib.core.Time function in grafanalib

# limitations under the License.

import re
import attr
from grafanalib import core as g

DECREASING_ORDER_TOOLTIP = g.Tooltip(sort=g.SORT_DESC)
PANEL_HEIGHT = g.Pixels(300)
QUANTILES = [0.99, 0.9, 0.5]

SOURCE_TEMPLATE = g.Template(name="source", type="datasource", query="prometheus")


@attr.s
class Dashboard(g.Dashboard):
    time = attr.ib(default=g.Time("now-30d", "now"))
    # Make it possible to use $source as a source.
    templating = attr.ib(default=g.Templating(list=[SOURCE_TEMPLATE]))


# Graph is a g.Graph with reasonable defaults applied.
@attr.s
class Graph(g.Graph):
    dataSource = attr.ib(default="$source")
    span = attr.ib(default=g.TOTAL_SPAN)
    tooltip = attr.ib(default=DECREASING_ORDER_TOOLTIP)
    nullPointMode = attr.ib(default=None)


@attr.s
class Row(g.Row):
    height = attr.ib(default=PANEL_HEIGHT)

links = attr.ib(default=attr.Factory(list))
    refresh = attr.ib(default=DEFAULT_REFRESH)
    schemaVersion = attr.ib(default=SCHEMA_VERSION)
    sharedCrosshair = attr.ib(
        default=False,
        validator=instance_of(bool),
    )
    style = attr.ib(default=DARK_STYLE)
    tags = attr.ib(default=attr.Factory(list))
    templating = attr.ib(
        default=attr.Factory(Templating),
        validator=instance_of(Templating),
    )
    time = attr.ib(
        default=attr.Factory(lambda: DEFAULT_TIME),
        validator=instance_of(Time),
    )
    timePicker = attr.ib(
        default=attr.Factory(lambda: DEFAULT_TIME_PICKER),
        validator=instance_of(TimePicker),
    )
    timezone = attr.ib(default=UTC)
    version = attr.ib(default=0)
    uid = attr.ib(default=None)

    def _iter_panels(self):
        for row in self.rows:
            for panel in row._iter_panels():
                yield panel

    def _map_panels(self, f):
        return attr.evolve(self, rows=[r._map_panels(f) for r in self.rows])

}


@attr.s
class Time(object):
    start = attr.ib()
    end = attr.ib()

    def to_json_data(self):
        return {
            'from': self.start,
            'to': self.end,
        }


DEFAULT_TIME = Time('now-1h', 'now')


@attr.s
class TimePicker(object):
    refreshIntervals = attr.ib()
    timeOptions = attr.ib()

    def to_json_data(self):
        return {
            'refresh_intervals': self.refreshIntervals,
            'time_options': self.timeOptions,
        }


DEFAULT_TIME_PICKER = TimePicker(
    refreshIntervals=[