Your self can raise errors in the program.
for example:
println('program started')
raise(Error('MyError', 'this is my error'))
println('this will not print')
output:
progrma started
MyError: this is my error
The raise function can raise errors in program.
You should pass a object from class Error as argument for this.
To do this, you need to write Error('TypeOfError', 'message of error'). You will learn about classes in next sections.