human
Can you provide a Python code to compare the transmission/reflection plot given the following:
I am working on the file "2.2.scattering.ipynb".
The first task is:
Your turn!
Copy the previous cell below this one and modify _wire in some way, e.g. by removing one site.  Compare the transmission/reflection plot.
Beyond the wire geometry
We are, of course, not restricted to a simplistic wire geometry.  Let's build a system that is a bit more complicated: a round quantum dot.
Can you write Python code for it?
assistant
#Here is Python code to compare the transmission/reflection plot.

def make_dot(center, radius, t=1):
    def is_inside(pos):
        x, y = pos - center
        return x**2 + y**2 < rr

    rr = radius**2
    syst = kwant.Builder()
    syst[lat.shape(is_inside, center)] = 4 * t
    syst[lat.neighbors()] = -t

    return syst