Might be a silly question, but how do you copy a BigFloat so that it is independent of the original?
julia> a=with_bigfloat_precision(()->BigFloat("0.1"),64)
1.00000000000000000001e-01 with 64 bits of precision
julia> z=copy(a)
1.00000000000000000001e-01 with 64 bits of precision
julia> a.d==z.d
true
julia> z=deepcopy(a)
1.00000000000000000001e-01 with 64 bits of precision
julia> a.d==z.d
true
