In debug compilation, assert takes in a Boolean condition as
a parameter, and shows the error dialog if the condition is
false. The program proceeds without any interruption if the
condition is true.

Assert is a method that can be called on code access 
permission classes and on the PermissionSet class. You can 
use Assert to enable your code (and downstream callers) to 
perform actions that your code has permission to do but its 
callers might not have permission to do. A security 
assertion changes the normal process that the runtime 
performs during a security check. When you assert a 
permission, it tells the security system not to check the 
callers of your code for the asserted permission.