Data containing NaN values

**How to display the nan values in the 3D data body as transparent or white colors when using 'volume_slice'?**
**In the below image, brown represents the area with nan value. How can I replace brown with transparent or white color？**
**Hope to receive an answer, thanks a lot!!!**
**my code is as follows:**
`import numpy as np`
`from mayavi import mlab`
`pre_cwt = np.load('predicted_Zp_better.npy')`
`fig = mlab.figure(figure='PI', bgcolor=(1, 1, 1), fgcolor=(0, 0, 0))`
`pre_cwt[pre_cwt == 0] = np.nan`
`scalars = pre_cwt # specifying the data array`
`mlab.volume_slice(scalars, slice_index=0, plane_orientation='x_axes', figure=fig, colormap='jet') # Time slice`
`mlab.volume_slice(scalars, slice_index=0, plane_orientation='y_axes', figure=fig, colormap='jet') # Inline slice`
`mlab.volume_slice(scalars, slice_index=0, plane_orientation='z_axes', figure=fig, colormap='jet') # Xline slice`
`mlab.axes(xlabel='Times(ms)', ylabel='Inline', zlabel='Xline', nb_labels=1) # Add axes labels`
`mlab.colorbar()`
`mlab.outline()`
`mlab.show()`