Building a Huffman Coding Tree using Python

huffman.py

#!/usr/bin/env python3
from pprint import pprint

def main():
    text = input()
    forest = []
    for letter in text:
        for tree in forest:
            if tree["letter"] == letter:
                break
        else:
            forest.append({"letter": letter,
                           "text": text,
                           "weight": text.count(letter)})
    forest = sorted(forest, key=lambda i:i["weight"])

    while len(forest) > 2:
        t1, t2, *rest = forest
        new_tree = {}
        new_tree["weight"] = t1["weight"] + t2["weight"]
        new_tree["left"] = t1
        new_tree["right"] = t2
        rest.append(new_tree)
        forest = rest
        forest = sorted(forest, key=lambda i:i["weight"])
    t1, t2 = forest
    tree = {}
    tree["weight"] = t1["weight"] + t2["weight"]
    tree["left"] = t1
    tree["right"] = t2
    pprint(tree)
    
main()