[LUA 5.1] assert

Issues an error when the value of its argument v is false (i.e., nil or false); otherwise, returns all its arguments. message is an error message; when absent, it defaults to "assertion failed!".

Example for assert

 can you give me an example where we use assert function ..........

Example for assert

textfile = assert (io.open ("example.txt", "w"))

assert can be used for example when trying to open a file for writing, if file doesn't exist, it will be automatically created.