Compute Synaptic Current I(t)

Loop through the first 5 time steps and print the synaptic current at each step.

Your task:
1. Set dt = 1e-3, i_mean = 25e-11
2. Loop range(5)
3. Compute t = step * dt
4. Compute i_t = i_mean * (1 + np.sin(2 * np.pi * t / 0.01))
5. Print: "step=0, t=0 ms, I=2.50e-10 A"

Expected output (5 lines):
step=0, t=0 ms, I=2.50e-10 A
step=1, t=1 ms, I=4.05e-10 A
step=2, t=2 ms, I=4.76e-10 A
step=3, t=3 ms, I=4.76e-10 A
step=4, t=4 ms, I=4.05e-10 A