old_contents: import numpy as np
  import matplotlib.pyplot as plt
  
  from pyvlm.airfoil import camber_gradient_NACA4
  
  # Plotting
  plt.style.use('ggplot')
  for x in np.linspace(0, 1, 21):
      dz = camber_gradient_NACA4(x)
      plt.plot(x, dz, 'ro')
      print(np.rad2deg(dz))
  plt.show()
  
new_contents: import numpy as np
  import matplotlib.pyplot as plt
  
  from pyvlm.airfoils import camber_gradient_NACA4
  
  # Plotting
  plt.style.use('ggplot')
  for x in np.linspace(0, 1, 21):
      dz = camber_gradient_NACA4(x)
      plt.plot(x, dz, 'ro')
      print(np.rad2deg(dz))
  plt.show()
  
subject: modify import