Optional argument,

that in computing such an argument, w hich can be specified in the subroutine call, or may be omitted f rom the specification of the value of this argument. Defining the sub-program [note 1], typically with sub-communication environme nt, a programmer at the same time declares the parameters of the subroutine. Most of you call this subroutine, should be specified list of arguments that will be associated with the parameters and used in the implementation of this subprogramme. These arguments are required and must be given to the source code.