Sampling and plotting total and stage resolved radiated powers with the ADAS subscription package.

```>>> import numpy as np
>>> import matplotlib.pyplot as plt

>>> from cherab.core.atomic import neon
>>> from cherab.core.math import sample2d_grid

>>> print("Testing total radiation for Neon.")

>>> electron_density = 1.e19
>>> electron_temperature = np.logspace(0, 4, 41)

>>> total_power = sample2d_grid(total_rad, electron_density, electron_temperature).squeeze()

>>> # Obtaining fractional abundance using ADAS405 code
>>> fractional_abundance = np.zeros((neon.atomic_number + 1, electron_temperature.size))
>>> for charge, abundance in enumerate(fractional_abundance):
>>>     fraction = atomic_data.fractional_abundance(neon, charge)
>>>     abundance[:] = sample2d_grid(fraction, electron_density, electron_temperature).squeeze()

>>> # Obtaining line and continuum radiation
>>> line_power = np.zeros((neon.atomic_number, electron_temperature.size))
>>> continuum_power = np.zeros((neon.atomic_number, electron_temperature.size))
>>> for charge in range(neon.atomic_number):
>>>     line_power[charge] = sample2d_grid(line_rad, electron_density, electron_temperature).squeeze() * fractional_abundance[charge]
>>>     continuum_power[charge] = sample2d_grid(continuum_rad, electron_density, electron_temperature).squeeze() * fractional_abundance[charge + 1]

>>> plt.figure()
>>> plt.plot(electron_temperature, total_power, '-k', label='Total radiation')
>>> plt.plot(electron_temperature, continuum_power.sum(0), ls=':', color='k', label='Recombination + Bremsstr.')
>>> plt.plot(electron_temperature, line_power.sum(0), ls=':', color='0.7', label='Total line radiation')
>>> for charge in range(line_power.shape[0]):
>>>     plt.plot(electron_temperature, line_power[charge], ls='--', label='Ne(+{}) line radiation'.format(charge))
>>> plt.xscale('log')
>>> plt.yscale('log')
>>> plt.ylim(1.e-39, 1.e-31)
>>> plt.xlabel("Electron Temperature (eV)")
>>> plt.ylabel("Power function (W m^3)")