A simple example

stack_overflow_41450957.py

import random
from bisect import bisect
from itertools import accumulate

class Struct:
    def __init__(self, alist):
        self.alist = alist


def main():
    example = Struct([1, 2, 3, 4, 5, 6, 7, 8, 9])

    arguments = {
        'arg_1': 2,
        'arg_2': 5,
    }

    apply_functions(example, arguments)


def apply_functions(data_struct, arguments):
    funcs = [func_1, func_2, func_3]
    weights = [1, 2, 3]

    func_weights = list(accumulate(weights))
    probability = bisect(func_weights, random.random() * func_weights[-1])
    funcs[probability](data_struct, **arguments)

    print(data_struct.alist)


def func_1(data_s, arg_1, **kwargs):
    print('func_1:', arg_1, kwargs)

def func_2(data_s, arg_2, **kwargs):
    print('func_2:', arg_2, kwargs)

def func_3(data_s, arg_1, arg_2, **kwargs):
    print('func_3:', arg_1, arg_2, kwargs)
    alist = data_s.alist
    temp = alist[:arg_1] + alist[arg_2:]
    point = random.randint(0, len(temp))
    data_s.alist[:] = temp[:point] + alist[arg_1:arg_2] + temp[point:]


if __name__ == '__main__':
    main()