How to save custom variable programmatically?

[Jean Louis]

I would like to use custom variables in such way to ask user
pragmatically, not through customize interface, to change a
variable. This could be for example user's location.

Upon changing it, I would like programatically to save it for future.

Should I use below function? Or maybe something else is recommended?

(defun customize-save-variable (variable value &optional comment)

  This way it is not working:
  
(require 'cus-edit)
(customize-save hyperscope-default-server "localhost")

Any good way?