Please consider my very first Julia function below.

It throws a "MethodError: no method matching zero(::Type{Any})"

and gives a list of three “Closest candidates”.

I do not understand how I can correct this error. Any help appreciated.

```
function b(u::Int, o::Int, t::Int)
if u == -o
return 1
end
if t == 0
return sum(b(u-j, o+j-1, (t+1) % 2) for j in 1:u)
end
return sum(b(u+j-1, o-j, (t+1) % 2) for j in 1:o)
end
function B(n::Int)
return b(n, 0, 0)
end
B(5)
```