old_contents: # coding: utf-8
  import numpy as np
  from scipy.stats.distributions import norm
  from mousestyles.kde import kde
  
  def test_kde():
      pdf = kde(x = np.array([2,3,1,0]), x_grid=np.linspace(0, 5, 10))
      assert (type(pdf) == np.ndarray)
      assert all([item >= 0 for item in pdf])
      assert (len(pdf) == 10)
      x1 = np.concatenate([norm(-1, 1.).rvs(400),
                      norm(1, 0.3).rvs(100)])
      pdf = kde(x = x1)
      assert (type(pdf) == np.ndarray)
      assert all([item >= 0 for item in pdf])
      assert (len(pdf) == 300)
new_contents: import numpy as np
  from scipy.stats.distributions import norm
  from mousestyles.kde import kde
  
  
  def test_kde():
      pdf = kde(x=np.array([2, 3, 1, 0]), x_grid=np.linspace(0, 5, 10))
      assert (type(pdf) == np.ndarray)
      assert all([item >= 0 for item in pdf])
      assert (len(pdf) == 10)
      x1 = np.concatenate([norm(-1, 1.).rvs(400),
                          norm(1, 0.3).rvs(100)])
      pdf = kde(x=x1)
      assert (type(pdf) == np.ndarray)
      assert all([item >= 0 for item in pdf])
      assert (len(pdf) == 300)
  
subject: modify code style for test function