def start_with(self, x):
           """Returns all arguments beginning with given string (or list thereof)"""

           _args = []

           for arg in self.all:
               if is_collection(x):
                   for _x in x:
                       if arg.startswith(x):
                           _args.append(arg)
                           break
               else:
                   if arg.startswith(x):
                       _args.append(arg)

           return Args(_args, no_argv=True)
Returns all arguments beginning with given string (or list thereof)