graphics(
    line(sin(x), (x, -pi, pi)),
    line(cos(x), (x, -pi, pi)))
# Expected:
## Plot object containing:
## [0]: cartesian line: sin(x) for x over (-3.141592653589793, 3.141592653589793)
## [1]: cartesian line: cos(x) for x over (-3.141592653589793, 3.141592653589793)