Running Python on Windows from Shell

So I've got some script named 'some_class.py' located in the same folder as python.exe:

from __future__ import print_function

class some_class:
    def say_it(self):
    print('hello')

def main():
    instance = some_class()
    instance.say_it()

if __name__ == '__main__':
    main()

When I try running it with the following command while in Python Shell inside PowerShell:

some_class.py

I get:

Traceback (most recent call last):
File "<stdin>", line 1, in <module>
NameError: name 'some_class' is not defined

Python's version is 3.4.1. What am I doing wrong?