Can someone help check why my python code doesn't run? I'm new to python and don't understand as to why I keep getting this error: NameError: name 'Planck' is not defined.

import numpy as np

# Spectral irradiance vs wavelength data

wavelength = np.linspace(0, 4000, 1000) # wavelength range in nm

spectral_irradiance = Planck(wavelength, T) # spectral irradiance data

# Integral of spectral irradiance over wavelength

integral_wavelength = np.trapz(spectral_irradiance, wavelength)

# Spectral irradiance vs energy data

energy = h*c/wavelength # energy data in eV

spectral_irradiance_eV = Planck(energy, T) # spectral irradiance data in eV

# Integral of spectral irradiance over energy

integral_energy = np.trapz(spectral_irradiance_eV, energy)

# Compare the two integrals

if abs(integral_wavelength - integral_energy) < 1e-5:

print("The integrals are identical.")

else:

print("The integrals are not identical.")