Please code in sage or python

a. Execute this example of a function definition: def h(x): return sum ([sin (n*x) for n in srange (1, 20.0)]) b. Evaluate h(x), and plot h(x) for x between 0 and 4*pi. c. Define a function that is equal to 2* x for x > 0, and equal to -3*x for x