Calling SheetMetal Commands from LISP code

In order to call the sheet metal command from LISP you usually have to compose a proper preselection: i.e. if a command expects an entity, a solid must be preselected, if a command works with faces, faces must be preselected.
Here you should exploit the fact that SmLispGet returns selection sets for features, so just right after a successful SmLispGet call you can call the required command, i.e. you can query faces of the flange first, and then call SmBendCreate to create bends on hard edges of the given flange

(SmLispGet "SelectEntities" "Top" "Flange_1")
(command "SmBendCreate")

Next, in your script you have to program a proper sequence of command options (if it has some modes) and finally you should check the return code by reading the errno variable. In our sample scripts we use three values:

(setq gError 79)
(setq gWarning 1)
(setq gSuccess 0)

Return code equal to 0 means the command is executed successfully.  79 means a fatal error has occurred, in which case it is better to stop the treatment of the model or the entire script and notify the user that the operation was unsuccessful, and the continuation of the scenario is not possible.
Warnings have to be treated up to context, they mean that command has succeeded, but some problems, which the system cannot resolve, have been detected.
Their treatment depends on the context: they can either be neglected or remembered to inform the user about some issues.
But the main point is that if you get a warning, you can continue the  scenario.
Let's continue the example to clarify the idea:

(SmLispGet "SelectEntities" "Top" "Flange_1")
(command "SmBendCreate")
(if (= gError (getvar "errno"))
  (progn
    (print "Failed to create bends! Exiting")
    (exit)
  )
)