How do I fourier transfrom sinc function and plot magnitude spectrum?

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?

By following just like this codes

fs = 10 # Sampling frequency

w = np.arange(-2 * np.pi, 2 * np.pi, 1 / fs) # frequency axis

N = len(w)

Xw = np.zeros(N)

T = 1

for i in range(-int(N/2), int(N/2)):

if i==0:

Xw[i + int(N/2)] = 1

if i!=0:

Xw[i + int(N/2)] = np.sin( i * T / 2 ) / ( i / 2 ) # CTFT coefficient