code: def test_thetalines_shape(theta):
      y = load_airline()
      t = ThetaLinesTransformer(theta)
      t.fit(y)
      actual = t.transform(y)
      assert actual.shape == (y.shape[0], len(theta))
  
imports: import numpy
  import pytest
  from scipy.stats import linregress
  from sktime.datasets import load_airline
  from sktime.transformations.series.theta import ThetaLinesTransformer
label_desc: Use image node_id 3 for calling a global function with example usage: test_thetalines_shape(theta) without return types