def linear_kernel(X, Y=None):
    X, Y = check_pairwise_arrays(X, Y)
    return safe_sparse_dot(X, Y.T, dense_output=True)
Test adding an OrderedDict item before a given key.
dataset/ETHPy150Open scikit-learn/scikit-learn/sklearn/metrics/pairwise.py/linear_kernel--crossover with--dataset/ETHPy150Open cloudera/hue/desktop/core/ext-py/markdown/regression-tests.py/TestOrderedDict.testAddBefore