Final answer:
The code provided is a python code snippet that uses the find() function to search for an empty string in the 'my_books' string. The output of the code will be 5.
Step-by-step explanation:
The code you provided is a Python code snippet. In this code, the variable my_books stores the string 'books 105'. The find() function is used to search for a substring within a string. The syntax of the find() function is string.find(substring, start, end).
In this code, '' is provided as the substring argument, which means it will search for an empty string. The start argument is set to 3, which means the search for the empty string will start from index 3 in the my_books string. The find() function returns the index of the first occurrence of the substring, or -1 if it is not found.
In this case, since the empty string is found at index 5 (after the space between 'books' and '105'), the output of the code will be 5.