dictionary.py

books = ['The Lord of the Rings', 'The Hobbit', 'Harry Potter and the Chamber of Secrets', 
        'Black Beauty', 'Kane and Abel', 'To Kill a Mocking Bird', 'Gitanjali', 
        'Spring and Autumn Annals', 'Rumi Poems'] # defining a list of books

book_catalog = {} # defining a dictionary

for book in books:
    book_index = book[0] # extract the first letter (for catalog)
    if book_index not in book_catalog:
        book_catalog[book_index] = [book]
    else:
        book_catalog[book_index].append(book) # appending the book if the index already exists in the catalog
        
book_catalog