A number wheel has:

 A name which is an uppercase letter.
 A set of ordered values which are either numbers or names.

A number is generated/yielded from a named wheel by:

1. Starting at the first value of the named wheel and advancing through subsequent values and wrapping around to the first value to form a "wheel":
1.a If the value is a number, yield it.
1.b If the value is a name, yield the next value from the named wheel
1.c Advance the position of this wheel.
Given the wheel

 A: 1 2 3
the number 1 is first generated, then 2, then 3, 1, 2, 3, 1, ...

Note: When more than one wheel is defined as a set of intersecting wheels then the
first named wheel is assumed to be the one that values are generated from.

Examples

Given the wheels:

   A: 1 B 2
   B: 3 4

The series of numbers generated starts:

   1, 3, 2, 1, 4, 2, 1, 3, 2, 1, 4, 2, 1, 3, 2...

The intersections of number wheels can be more complex, (and might loop forever),
and wheels may be multiply connected. 


Note: If a named wheel is referenced more than
once by one or many other wheels, then there is only one position of the wheel
that is advanced by each and all references to it.

E.g.

 A:  1 D D
 D:  6 7 8
 Generates:
   1 6 7 1 8 6 1 7 8 1 6 7 1 8 6 1 7 8 1 6 ...    

Task

Generate and show the first twenty terms of the sequence of numbers generated
from these groups:

   Intersecting Number Wheel group:
     A:  1 2 3
   
   Intersecting Number Wheel group:
     A:  1 B 2
     B:  3 4
   
   Intersecting Number Wheel group:
     A:  1 D D
     D:  6 7 8
   
   Intersecting Number Wheel group:
     A:  1 B C
     B:  3 4
     C:  5 B

Show your output here, on this page.



const d1 = Dict("A" => [["1", "2", "3"], 1])
const d2 = Dict("A" => [["1", "B", "2"], 1], "B" => [["3", "4"], 1])
const d3 = Dict("A" => [["1", "D", "D"], 1], "D" => [["6", "7", "8"], 1])
const d4 = Dict("A" => [["1", "B", "C"], 1], "B" => [["3", "4"], 1],
    "C" => [["5", "B"], 1])
 
function getvalue!(wheelname, allwheels)
    wheel = allwheels[wheelname]
    s = wheel[1][wheel[2]]
    wheel[2] = mod1(wheel[2] + 1, length(wheel[1]))
    return haskey(allwheels, s) ? getvalue!(s, allwheels) : s
end
 
function testwheels(wheels, numterms = 20, firstwheel = "A")
    println("\nNumber Wheels:")
    for k in sort(collect(keys(wheels)))
        print("$k: [")
        for s in wheels[k][1]
            print(s, " ")
        end
        println("\b]")
    end
    print("Output: ")
    for _ in 1:numterms
        print(getvalue!(firstwheel, wheels), " ")
    end
    println("...")
end
 
foreach(testwheels, [d1, d2, d3, d4])
 