Is it possible to know if a function has captured local variables?

General Usage
8

Okay, it seems that it’s not about whether the constructed function is a closure, but about how the global variable is embedded in the function body, which is even more confusing now:

julia> d = fill(1)
0-dimensional Array{Int64, 0}:
1

julia> function f3()
           function (y)
           d[] + y
           end
       end
f3 (generic function with 1 method)

julia> f3c = f3()
#3 (generic function with 1 method)

julia> f3c(1)
2

julia> d[] += 1
2

julia> f3c(1)
3

julia> f3c_dc = deepcopy(f3c)
#3 (generic function with 1 method)

julia> f3c_dc(1)
3

julia> d[] += 1
3

julia> f3c_dc(1)
4

julia> f3c(1)
4