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 fit(
      self,
      X,
      y=None,
      time_col=TIME_COL,
      value_col=VALUE_COL,
      **fit_params,
  ):
      super().fit(X, y=y, time_col=time_col, value_col=value_col)
  
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 2 for calling the ConstantBaseForecastEstimator obj's underlying member method code with example usage: obj.fit(X, y, time_col, value_col) without return types