How to draw a semicircle in Python turtle only

See Python turtle reference on circle. For example, for a semi-circle with radius 100 it would be:

import turtle
turtle.circle(100,180)

Try the following:

import turtle
t = turtle.Pen()
t.left(90)
for x in range(180):
    t.forward(1)
    t.right(1)
t.right(90)
t.forward(115)