n_periods must be an int

This error usually occurs in Python when you are trying to pass a non-integer value to a function that expects an integer argument for the number of periods. To fix this error, you can convert the non-integer value to an integer using the int() function. For example:

n_periods = int(n_periods)

This will convert the value of n_periods to an integer and allow you to pass it to the function without triggering the error.