def METHOD_NAME(P,PB,T,QVAPOR):
	''' Program to calculate equivalent potential temperature using WRF
	variables P, PB, T, QVAPOR.
	Calling sequence:  WRF_ETH = ETH(P,PB,T,QVAPOR)
	Result WRF_ETH is a 3D variable on same grid as P,PB,T,QVAPOR.'''