Run Python Script; Nothing Happens

[ryguy7272]

I am using Spyder Python 2.7.  I'm running this sample code.
import numpy as np
import numpy.random as npr
import matplotlib.pyplot as plt
S0 = 100
r = 0.05
sigma = 0.25
T = 30 / 365.
I = 10000
ST = S0 * np.exp((r - 0.5 * sigma ** 2) * T + sigma * np.sqrt(T) * npr.standard_normal(I))
R_gbm = np.sort(ST - S0)
plt.hist(R_gbm, bins=50)
plt.xlabel('absolute return')
plt.ylabel('frequency')
plt.grid(True)

I found it in a book, and I'm trying to run various samples of code, in an effort to learn Python.  So, I click the debug button, and this is what I get.
> c:\users\rshuell001\untitled12.py(1)<module>()
-> import numpy as np
(Pdb) 
 
It seems like it doesn't really do anything.  So, I click the exit debug button and then click the run button and nothing happens.  I get nothing at all.  In the book, the author got a graph.  I get nothing.  I think, and I could be totally wrong, Python is sending something to a Console, but I can't tell where it goes.  I opened every Console I could find, and I still see nothing happening whatsoever.

Any idea what's wrong here?