# An error in implementation of "for" loop while using "IntervalArithmetic.jl" package in "Pluto.jl" notebook

Hello

I am trying to find a root of an equation using Interval Newton method in Julia. I am using “IntervalArithmetic.jl” package in “Pluto.jl” notebook. The code seems logically correct (checked a few times) but it is giving an error `syntax: "for" at /Users/dycobs/.julia/pluto_notebooks/Mini revelation.jl#==#4e903eeb-0172-4cd3-b5e9-21d235f99d28:13 expected "end", got "NXk"`
The code is here

``````begin
using IntervalArithmetic, Plots, ForwardDiff, PlutoUI, FiniteDiff

f(x) = a - b * x

l = 10
m = 10
a1 = vec(mince(100..200, l))
b1 = vec(mince(1..2, m))

d(f, x) = ForwardDiff.derivative(f, x)
local Xnew = 0..300
nn = 10
NXk = (0..0)
for i in 1:nn
for j in 1:l
a = a1[j]
for k in 1:m
b = b1[k]
NXk_new = mid(Xnew) - (f(mid(Xnew)) / d(f, Xnew))
NXk = NXk ∪ NXk_new
end
end
Xkplus NXk ∩ Xnew
Xnew = Xkplus
@show(interval(i), Xnew)
end
end
``````

Could you please explain the possible reason behind the error?

Thank you

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