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Given the following text description, write Python code to implement the functionality described below step by step
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Description:
 Permutation Promenade
Part 1
Step1:  Test
Step2:  Solution
Step3:  Part 2
It may not be necessary to carry out the insanely big $10^9$ rounds of shuffling. We will search for the order of the shuffling process, i.e., the minimum number of rounds for which the programs are arranged as they were at the start. Then we will mod $n$.
Step4:  Test
Step5:  Solution
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Python Code:
with open('input.txt', 'rt') as f:
    moves = next(f).rstrip().split(',')
import re
import numpy as np
import copy
def shuffle(p, moves):
    s = copy.copy(p)
    for move in moves:
        spin = re.search('s(\d+)', move)
        swapx = re.search('x(\d+)\/(\d+)', move)
        swapp = re.search('p(\w)\/(\w)', move)
        if spin:
            s = np.roll(s, int(spin.group(1)))
        if swapx:
            a = int(swapx.group(1))
            b = int(swapx.group(2))
            s[a], s[b] = s[b], s[a]
        if swapp:
            a = swapp.group(1)
            b = swapp.group(2)
            a = ''.join(s).index(a)
            b = ''.join(s).index(b)
            s[a], s[b] = s[b], s[a]
    return ''.join(s)
Explanation: Permutation Promenade
Part 1
End of explanation
assert(shuffle(list('abcde'), ['s1', 'x3/4', 'pe/b']) == 'baedc')
Explanation: Test
End of explanation
shuffle(list('abcdefghijklmnop'), moves)
Explanation: Solution
End of explanation
from itertools import count
def least_fixed_point(s, moves):
    a = s
    b = shuffle(list(s), moves)
    visited = [s]
    for i in count():
        if b not in visited:
            visited.append(b)
            a = b
            b = shuffle(list(b), moves)
        else:
            return a, i
def iterated_dances(s, moves, N):
    for i in range(N):
        s = shuffle(list(s), moves)
    return s
Explanation: Part 2
It may not be necessary to carry out the insanely big $10^9$ rounds of shuffling. We will search for the order of the shuffling process, i.e., the minimum number of rounds for which the programs are arranged as they were at the start. Then we will mod $n$.
End of explanation
least_fixed_point(list('abcde'), ['s1', 'x3/4', 'pe/b'])
iterated_dances(list('abcde'), ['s1', 'x3/4', 'pe/b'], 4)
Explanation: Test
End of explanation
s = 'abcdefghijklmnop'
least_fixed_point(list(s), moves)
iterated_dances(list(s), moves, (10 ** 9) % 60)
Explanation: Solution
End of explanation
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