substitution for class | Python Fiddle

import random
encrypt_table={}

def generate_table():
    plain_list=[]
    random_list=[]
    for i in range(65,91): #all of ascii
        plain_list+=[chr(i)] #creating ascii chars and adding to plain_string 
    random_list=plain_list[:] #copy of list so that we can make a separate shuffled version
    random.shuffle(random_list)  #shuffle list 
    for i in range(0, len(plain_list)): #iterate over each letter in the alphabetical list
        encrypt_table[plain_list[i]]=random_list[i] #index assign from each list in order
    return encrypt_table

def reverse_table(encrypt_table): 
    for x in encrypt_table:  #iterate through each set of translation table entries
        reverse_table[encrypt_table[x]]=x #reverse table keys will equal the values of encrypt table
    return reverse_table

def string_to_table(table_string):
    s_list=list(table_string) #splits the string into list items
    return list_table

def table_to_string(table):
    for i in table:  
        stringoftable+=str(table[i]) #inserting values in the table as concatenated strings, one by one
	return stringoftable

table=generate_table()
string=table_to_string(table)

def encrypt(table, string):

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