example of modules and scripting

data.py

# this part is executed when you load it
a = 0
while a < 10:
    a++

# now we could have executed whatever here, read a file
# reboot the system, not so nice and the reason you
# should read a dependency to make sure you are not
# going to kill yourself

def fetch():
    return a # a is 10

if __name__ == '__main__':
    # this is a conditional execution
    # if you run python data.py it gets
    # executed
    print(a)

main.py

# we are importing the names in data.py into
# our environment, what happens next is that
# the file data.py gets interepreted and we
# bind the name fetch from that module to the
# name fetch in this module
from data import fetch # as my_fetch # this would bind fetch to another name

if __name__ == '__main__':
    d = fetch()