# type: ignore
import pickle, os
# This is a demo for using pickle to store objects as files for later executions

# This should work whether you're using sage or python, and similar things can
# be done in other programming languages

# In this demo we just store an integer, but we can store much more complex objects as well

# Standin for some long running function
def big_calc():
    return 10

# We check whether there is a bigobj file already
if os.path.isfile("bigobj"):
    # If the file exists we open it and use pickle to load its contents
    # to the variable N
    f = open("bigobj", "rb") # open bigobj in binary read mode
    N = pickle.load(f)
else:
    # If the file doesn't exist we do the computation, create the file
    # and store the value of the variable into the file
    N = big_calc() 
    f = open("bigobj", "wb") # open bigobj in binary write mode
    pickle.dump(N, f)

# To recompute N if its value should change you can simply delete the bigobj file