string.find_last_of

As an AI language model, I don't know which programming language you are referring to. However, I can explain the general concept of the "find_last_of" function.

In many programming languages, "find_last_of" is a string function that returns the index of the last occurrence of a character or substring in a string. It searches the string from the end towards the beginning until it finds the specified character or substring. If the character or substring is not found, it returns a special value such as -1.

For example, in Python, the "find_last_of" function is called "rfind". Here is an example of how to use it:

string = "hello world"
index = string.rfind("o")
print(index)  # prints 7

In this example, the "rfind" function returns the index of the last occurrence of the letter "o" in the string "hello world", which is 7.