UndefVarError in `bidrand(d::GaussianLaguerre, n::Int)`

Comes from `chi` function:
```
function bidrand(d::GaussianLaguerre, m::Integer)
if d.a <= d.beta*(m-1)/2.0
error("Given your choice of m and beta, a must be at least $(d.beta*(m-1)/2.0) (You said a = $(d.a))")
end
Bidiagonal([chi(2*d.a-i*d.beta) for i=0:m-1], [chi(d.beta*i) for i=m-1:-1:1], true)
end
```
Perhaps its from Distributions.jl?

Start by locating the bidrand(d::GaussianLaguerre, m::Integer) entry point and the chi function it calls. Reproduce the UndefVarError, determine whether chi is provided by this package or Distributions.jl, and confirm that bidrand works for the reported GaussianLaguerre inputs.

Do mô hình lập chỉ mục viết ra từ nội dung của issue.