code: def test_proj():
      pca = KPCA(n_components=2)
      pca.fit(X1[:2])
      exp = np.array([[-0.71, -0.71], [0.71, -0.71]])
      assert_almost_equal(pca.X_projected_, exp, decimal=2)
  
file_path: mlxtend/mlxtend/feature_extraction/tests/test_kernel_pca.py
imports: import numpy
  import pytest
  from numpy.testing import assert_almost_equal
  from sklearn.datasets import make_moons
  from mlxtend.feature_extraction import RBFKernelPCA
label_desc: Use image node_id 4 for calling a global function with example usage: test_proj() without return types