function deriveorder(m)
    out = String[]
    while length(m) > 0
        #  find the right value for x
        lenarr = Vector{String}(length(m))
        for (k, v) in m
            len = length(v)
            lenarr[len] = k
        end
        x = m[lenarr[1]]  # x is equal to the element present in all arrays
        append!(out, x)
        for (k, v) in m  # iterate through all arrays in m
            for (i, j) in enumerate(v)  # iterate through elements in arrays
                if [j] == x
                    global xind = i  # store index whose element is equal to x
                end
            end
            deleteat!(m[k], xind) # delete element equal to x in array k
            if length(m[k]) == 0  # if k is an empty array, delete it from m
                delete!(m, k)
            end
        end
    end
    return out
end