How do I fourier transfrom sinc function by Python's numpy.fft.fft?

Hello, I'm trying to write a Python code to verify the fourier transform’s duality by transforming the following sync functions.

The given sinc function was created by fourier transforming this square pulse.

and I got this sinc funtion which is represented by np.sin(i*T/2)/(i/2)

How do I write code that transforms this sinc function to square pulse by using np.fft.fft of numpy?