code: def test_l1_quantile_regression(data):
      """Tests L1 norm regularized quantile regression."""
      coef = l1_quantile_regression(
          x=data["x"],
          y=data["y"],
          q=0.1,
          alpha=1,
          sample_weight=np.ones(len(data["y"])),
          feature_weight=np.ones(data["x"].shape[1]),
          include_intercept=True,
      )
      pred = data["x"] @ coef["coef"] + coef["intercept"]
      coef1 = l1_quantile_regression(
          x=data["x"],
          y=data["y"],
          q=0.9,
          alpha=1,
          sample_weight=np.ones(len(data["y"])),
          feature_weight=np.ones(data["x"].shape[1]),
          include_intercept=True,
      )
      pred1 = data["x"] @ coef1["coef"] + coef1["intercept"]
      assert all(pred1 > pred)
  
file_path: greykite/greykite/tests/algo/common/test_l1_quantile_regression.py
imports: import numpy
  import pytest
  from testfixtures import LogCapture
  from greykite.algo.common.l1_quantile_regression import QuantileRegression
  from greykite.algo.common.l1_quantile_regression import l1_quantile_regression
  from greykite.algo.common.l1_quantile_regression import ordinary_quantile_regression
  from greykite.common.logging import LOGGER_NAME
label_desc: Use image node_id 3 for calling a global function with example usage: test_l1_quantile_regression(data) without return types