class_docstr: Simple estimator that predicts a constant (the weekday of the first date in
  ``X`` passed to ``predict``).
  Used to test BaseForecastEstimator methods, since abstract classes can't be instantiated.
class_docstr_tok: ["Simple","estimator","that","predicts","a","constant","(","the","weekday","of","the","first","date","in","``","X","``","passed","to","``","predict","``",")",".","Used","to","test","BaseForecastEstimator","methods",",","since","abstract","classes","ca","n't","be","instantiated","."]
code: def __init__(
      self,
      score_func=mean_squared_error,
      coverage=0.95,
      null_model_params=None,
  ):
      super().__init__(
          score_func=score_func,
          coverage=coverage,
          null_model_params=null_model_params,
      )
  
imports: import numpy
  import pandas
  import pytest
  from pandas.testing import assert_frame_equal
  from sklearn.metrics import mean_absolute_error
  from sklearn.metrics import mean_squared_error
  from testfixtures import LogCapture
  from greykite.common.constants import LOGGER_NAME
  from greykite.common.constants import PREDICTED_COL
  from greykite.common.constants import PREDICTED_LOWER_COL
  from greykite.common.constants import PREDICTED_UPPER_COL
  from greykite.common.constants import TIME_COL
  from greykite.common.constants import VALUE_COL
  from greykite.common.evaluation import r2_null_model_score
  from greykite.sklearn.estimator.base_forecast_estimator import BaseForecastEstimator
  from greykite.sklearn.uncertainty.uncertainty_methods import UncertaintyMethodEnum
label_desc: Use image node_id 1 to create a new ConstantBaseForecastEstimator object from inherited base classes: BaseForecastEstimator with example: obj = ConstantBaseForecastEstimator(score_func, coverage, null_model_params)