missing imaginary protion in FFT

I was reading FFT chapter and looking at

Xk=∑N−1n=0xn⋅e−2πkn/N
and
xn=1N∑N−1k=0Xk⋅e2πkn/N

where did the imaginary numbers go?
it was in the integral before and in the code after the discrete fourier transform