ErrorName: Window size

[jvlivz]

Hello all of you. My name is Julio and I am new in python. Today I want to post this because I have a big problem with my code and I can't find the real problem.
The code that I'm using in gedit is this:

from math import pi, sin

window_size(500, 500)
window_coordinates(-2*pi, -1.5, 2*pi, 1.5)

create_point(-2*pi, sin(-2*pi))
create_point(-1.5*pi, sin(-1.5*pi))
create_point(-pi, sin(-pi))
create_point(-0.5*pi, sin(-0.5*pi))
create_point(0, sin(0))
create_point(0.5*pi, sin(0.5*pi))
create_point(pi, sin(pi))
create_point(1.5*pi, sin(1.5*pi))
create_point(2*pi, sin(2*pi))

And the error that I get once I run the program on python console is the next:

Error:
Traceback (most recent call last):
File "ejemplo2.py", line 4, in <module>
window_size(500, 500)
NameError: name 'window_size' is not defined

I've been looking on the web any help to solve the problem but I still have not found any good support, hope you guys could help me to fix it.
thank's