# File: userstring-example-1.py

import UserString

class MyString(UserString.MutableString):

    def append(self, s):
        self.data = self.data + s

    def insert(self, index, s):
        self.data = self.data[index:] + s + self.data[index:]

    def remove(self, s):
        self.data = self.data.replace(s, "")

file = open("samples/book.txt")
text = file.read()
file.close()

book = MyString(text)

for bird in ["gannet", "robin", "nuthatch"]:
    book.remove(bird)

print book