I've tried to create a random password generator with Python but the output returned blank. I'm new to Python and, therefore, can't see where I made a mistake.

```
import random
    letters = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z']
    numbers = ['0', '1', '2', '3', '4', '5', '6', '7', '8', '9']
    symbols = ['!', '#', '$', '%', '&', '(', ')', '*', '+']

    print("Welcome to the PyPassword Generator!")
    nr_letters= int(input("How many letters would you like in your password?\n")) 
    nr_symbols = int(input(f"How many symbols would you like?\n"))
    nr_numbers = int(input(f"How many numbers would you like?\n"))

    characters = [letters, symbols, numbers]

    password = ""
#Password within the boundaries
    letter_count = 0
    symbol_count = 0
    number_count = 0

    for char in characters[random.randint(0, 2)]:

      if letters == char and letter_count <= nr_letters:
          password += letters[random.randint(0, 47)]
          letter_count += 1

      elif symbols == char and symbol_count <= nr_symbols:
          password += symbols[random.randint(0, 8)]
          symbol_count += 1

      elif numbers == char and number_count <= nr_numbers:
          password += numbers[random.randint(0, 9)]
          number_count += 1

      if len(password) == nr_letters + nr_symbols + nr_numbers:
        break
    print(password)

```