old_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))
      # check function kde returns an np.ndarray
      assert (type(pdf) == np.ndarray)
      # check function kde returns array with all nonnegative numbers
      assert all([item >= 0 for item in pdf])
      # check function kde returns array with length the same as length of x_grid
      assert (len(pdf) == 10)
  
      x1 = np.concatenate([norm(-1, 1.).rvs(400),
                          norm(1, 0.3).rvs(100)])
      
      # check kde works fine for a more complicated input, and the default value
      # of x_grid works fine
      pdf = kde(x=x1, x_grid=np.linspace(0, 5, 10))
      # check function kde returns an np.ndarray
      assert (type(pdf) == np.ndarray)
      # check function kde returns array with all nonnegative numbers
      assert all([item >= 0 for item in pdf])
      # check function kde returns array with length the same as length of x_grid
      assert (len(pdf) == 10)
      
      pdf = kde(x=x1, x_grid=np.linspace(0, 5, 100), symmetric_correction
                =True, cutoff=1)
      # check function kde returns an np.ndarray
      assert (type(pdf) == np.ndarray)
      # check function kde returns array with all nonnegative numbers
      assert all([item >= 0 for item in pdf])
      # check function kde returns array with length the same as length of x_grid
      assert (len(pdf) == 100)
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))
      # check function kde returns an np.ndarray
      assert (type(pdf) == np.ndarray)
      # check function kde returns array with all nonnegative numbers
      assert all([item >= 0 for item in pdf])
      # check function kde returns array with length the same as length of x_grid
      assert (len(pdf) == 10)
  
      x1 = np.concatenate([norm(-1, 1.).rvs(400),
                          norm(1, 0.3).rvs(100)])
      # check kde works fine for a more complicated input, and the default value
      # of x_grid works fine
      pdf = kde(x=x1, x_grid=np.linspace(0, 5, 10))
      # check function kde returns an np.ndarray
      assert (type(pdf) == np.ndarray)
      # check function kde returns array with all nonnegative numbers
      assert all([item >= 0 for item in pdf])
      # check function kde returns array with length the same as length of x_grid
      assert (len(pdf) == 10)
  
      pdf = kde(x=x1, x_grid=np.linspace(0, 5, 100),
                symmetric_correction=True, cutoff=1)
      # check function kde returns an np.ndarray
      assert (type(pdf) == np.ndarray)
      # check function kde returns array with all nonnegative numbers
      assert all([item >= 0 for item in pdf])
      # check function kde returns array with length the same as length of x_grid
      assert (len(pdf) == 100)
  
subject: modify code style