@testset "4 Trig functions" begin
    include("4.1 Sine/.jl")
    include("4.2 Cosine/.jl")
    include("4.3 Tangent/.jl")
    include("4.4 Cotangent/.jl")
    include("4.5 Secant/.jl")
    include("4.6 Cosecant/.jl")
    include("4.7 Miscellaneous/.jl")
end
