Newbie: Check first two non-whitespace characters

[Random832]

otaksoftspamtrap at gmail.com writes:
> I need to check a string over which I have no control for the first 2
> non-white space characters (which should be '[{').
>
> The string would ideally be: '[{...' but could also be something like 
> '  [  {  ....'.
>
> Best to use re and how? Something else?

Is it an arbitrary string, or is it a JSON object consisting of a list
whose first element is a dictionary? Because if you're planning on
reading it as a JSON object later you could just validate the types
after you've parsed it.