Named arguments without natural defaults in Julia

Could do the following:

function discount_rate(;n=nothing,fv=nothing,pmt=nothing,pv=nothing,pmt_type=0)
    if n == nothing || fv == nothing || pmt == nothing || pv == nothing
        error("Must provide all arguments")
    end
    discount_rate(n,fv,pmt,pv,pmt_type=pmt_type)
end

function discount_rate(n, fv, pmt, pv; pmt_type = 0)
    #...
end