CALL subroutine-name ( [ expression [ , expression ... ] ] )

   Synopsis:
      Calls a subroutine with the specified arguments

   Notes:
      The arguments, if any, must match those in the SUB statement at the
         beginning of the subroutine profile, both in type and number.

      In a statement like:
      
         CALL mysub (...)
         
      ...the subroutine's return value, if any, is ignored.
      
      However, CALL can also be used in LET statements to capture return values:
      
         LET result$ = CALL mysub (...)
         result$ = CALL mysub (...)
         
      Note that CALL is a statement, not a function, so it cannot be used thus:
      
         PRINT 10 * (CALL mysub (...))

   Availability:
      CALL is not available in scripts with primitive line numbers.

   Examples:
      LET number1 = 2
      LET number2 = 5
      LET result = CALL multiply (number1, number2)
      PRINT result
      END

      SUB NUMERIC multiply (val1, val2)
         RETURN (val1 * val2)
      END SUB
