The SEQUENTIAL_GUARD statement (SGUARD)
This statement has the same syntax as the GUARD statement, but guarantees that multiple executions of the function it GUARDs will take place in order. This is required for I/O routines and some special arithmetical procedures such as random number generators.
Normally, a FALCON program is compiled into a main program: a program that runs by itself after being invoked from the computer's operating system.
If a FALCON program begins with a FUNCTION, or SUBROUTINE statement, however, it is instead compiled to form an external procedure of the requested type. It is necessary at this point to digress from function-related statements within the calling program to examine these statements, because we will next proceed to a class of statements that combines, for example, the function of an XFUN statement with that of a FUNCTION statement.