code: def get_shifted_qtrs(self, zero_qtrs, num_announcements):
      return zero_qtrs - (num_announcements - 1)
  
imports: from abc import abstractmethod, abstractproperty
  import numpy
  import pandas
  from six import viewvalues
  from toolz import groupby
  from catalyst.lib.adjusted_array import AdjustedArray
  from catalyst.lib.adjustment import Datetime641DArrayOverwrite, Datetime64Overwrite, Float641DArrayOverwrite, Float64Multiply, Float64Overwrite
  from catalyst.pipeline.common import EVENT_DATE_FIELD_NAME, FISCAL_QUARTER_FIELD_NAME, FISCAL_YEAR_FIELD_NAME, SID_FIELD_NAME, TS_FIELD_NAME
  from catalyst.pipeline.loaders.base import PipelineLoader
  from catalyst.utils.numpy_utils import datetime64ns_dtype, float64_dtype
  from catalyst.pipeline.loaders.utils import ffill_across_cols, last_in_date_group
label_desc: Use image node_id 2 for calling the PreviousEarningsEstimatesLoader obj's underlying member method code with example usage: obj.get_shifted_qtrs(zero_qtrs, num_announcements) and returns: unknown