code: def _format_coord(freq, t, y):
      return "t = {0}  y = {1:8f}".format(
          Period(ordinal=int(t), freq=freq), y
      )
  
imports: import functools
  from matplotlib import pylab
  import numpy
  from pandas._libs.tslibs.frequencies import FreqGroup, get_base_alias, get_freq, is_subperiod, is_superperiod
  from pandas._libs.tslibs.period import Period
  import pandas.compat
  from pandas.core.dtypes.generic import ABCDatetimeIndex, ABCPeriodIndex, ABCTimedeltaIndex
  from pandas.io.formats.printing import pprint_thing
  from pandas.plotting._converter import TimeSeries_DateFormatter, TimeSeries_DateLocator, TimeSeries_TimedeltaFormatter
  import pandas.tseries.frequencies
  from pandas.tseries.offsets import DateOffset
label_desc: Use image node_id 14 for calling a global function with example usage: _format_coord(freq, t, y) and returns: str