code: def T(s):
      return pd.Timestamp(s, tz="UTC")
  
imports: from itertools import cycle, islice
  from nose_parameterized import parameterized
  import numpy
  import pandas
  from trading_calendars import get_calendar
  from zipline.assets.synthetic import make_rotating_equity_info
  from zipline.data.in_memory_daily_bars import InMemoryDailyBarReader
  from zipline.pipeline.domain import CA_EQUITIES, GB_EQUITIES, US_EQUITIES
  from zipline.pipeline import Pipeline
  from zipline.pipeline.data import EquityPricing, USEquityPricing
  from zipline.pipeline.engine import SimplePipelineEngine
  from zipline.pipeline.loaders.equity_pricing_loader import EquityPricingLoader
  from zipline.pipeline.loaders.synthetic import NullAdjustmentReader
  from zipline.testing.predicates import assert_equal
  from zipline.testing.core import parameter_space, random_tick_prices
  import zipline.testing.fixtures
label_desc: Use image node_id 1 for calling a global function with example usage: T(s) and returns: pd