For python 3.6 and above using secrets module

password_generator.py

@@ -7,7 +7,6 @@
 """
 
 import string
-# import random
 from copy import deepcopy
 from random import shuffle, randint
 
@@ -17,7 +16,7 @@
     from random import choice
 
 
-class PasswordGenerator():
+class PasswordGenerator:
     """
 
     We can set properties such as
@@ -54,46 +53,97 @@ def __init__(self):
         self.lower_chars = string.ascii_lowercase
         self.upper_chars = string.ascii_uppercase
         self.numbers_list = string.digits
-        self._schars = ['!','#','$','%', '^', '&', '*', '(', ')', ',', '.', '-', '_', '+', '=', '<', '>', '?']
-        self._allchars = list(self.lower_chars) + list(self.upper_chars) + list(self.numbers_list) + self._schars
-
+        self._schars = [
+            "!",
+            "#",
+            "$",
+            "%",
+            "^",
+            "&",
+            "*",
+            "(",
+            ")",
+            ",",
+            ".",
+            "-",
+            "_",
+            "+",
+            "=",
+            "<",
+            ">",
+            "?",
+        ]
+        self._allchars = (
+            list(self.lower_chars)
+            + list(self.upper_chars)
+            + list(self.numbers_list)
+            + self._schars
+        )
 
     def generate(self):
         """Generates a password using default or custom properties"""
-        if self.minlen < 0 or self.maxlen < 0 or self.minuchars < 0 or self.minlchars < 0 or  self.minnumbers < 0 or self.minschars < 0 :
+        if (
+            self.minlen < 0
+            or self.maxlen < 0
+            or self.minuchars < 0
+            or self.minlchars < 0
+            or self.minnumbers < 0
+            or self.minschars < 0
+        ):
             raise ValueError("Character length should not be negative")
 
         if self.minlen > self.maxlen:
-            raise ValueError("Minimum length cannot be greater than maximum length. The default maximum length is 16.")
+            raise ValueError(
+                "Minimum length cannot be greater than maximum length. The default maximum length is 16."
+            )
 
-        collectiveMinLength = self.minuchars + self.minlchars + self.minnumbers + self.minschars
+        collectiveMinLength = (
+            self.minuchars + self.minlchars + self.minnumbers + self.minschars
+        )
 
         if collectiveMinLength > self.minlen:
             self.minlen = collectiveMinLength
 
-        final_pass = [choice(list(set(self.lower_chars) - set(self.excludelchars))) for i in range(self.minlchars)]
-        final_pass += [choice(list(set(self.upper_chars) - set(self.excludeuchars))) for i in range(self.minuchars)]
-        final_pass += [choice(list(set(self.numbers_list) - set(self.excludenumbers))) for i in range(self.minnumbers)]
-        final_pass += [choice(list(set(self._schars) - set(self.excludeschars))) for i in range(self.minschars)]
-
+        final_pass = [
+            choice(list(set(self.lower_chars) - set(self.excludelchars)))
+            for i in range(self.minlchars)
+        ]
+        final_pass += [
+            choice(list(set(self.upper_chars) - set(self.excludeuchars)))
+            for i in range(self.minuchars)
+        ]
+        final_pass += [
+            choice(list(set(self.numbers_list) - set(self.excludenumbers)))
+            for i in range(self.minnumbers)
+        ]
+        final_pass += [
+            choice(list(set(self._schars) - set(self.excludeschars)))
+            for i in range(self.minschars)
+        ]
 
         currentpasslen = len(final_pass)
-        all_chars = list(set(self._allchars) - set(list(self.excludelchars) + list(self.excludeuchars) + list(self.excludenumbers) + list(self.excludeschars)))
+        all_chars = list(
+            set(self._allchars)
+            - set(
+                list(self.excludelchars)
+                + list(self.excludeuchars)
+                + list(self.excludenumbers)
+                + list(self.excludeschars)
+            )
+        )
 
         if len(final_pass) < self.maxlen:
             randlen = randint(self.minlen, self.maxlen)
-            final_pass += [choice(all_chars) for i in range(randlen-currentpasslen)]
+            final_pass += [choice(all_chars) for i in range(randlen - currentpasslen)]
 
         shuffle(final_pass)
-        return ''.join(final_pass)
-
+        return "".join(final_pass)
 
     def shuffle_password(self, password, maxlen):
         """Shuffle the given charactes and return a password from given characters."""
         final_pass = [choice(list(password)) for i in range(int(maxlen))]
         shuffle(final_pass)
-        return ''.join(final_pass)
-
+        return "".join(final_pass)
 
     def non_duplicate_password(self, maxlen):
         """Generate a non duplicate key of given length"""
@@ -106,7 +156,7 @@ def non_duplicate_password(self, maxlen):
                 final_pass.append(character)
                 allchars.pop(element_index)
         except IndexError as e:
-            raise ValueError('Length should less than 77 characters.')
-            
+            raise ValueError("Length should less than 77 characters.")
+
         shuffle(final_pass)
-        return ''.join(final_pass)
+        return "".join(final_pass)