let get_lines_indentation ?(indent_spec=default_indent) s =
let lexbuf = Lexing.from_string s in
blocks := [];
line_indentations := [];
next_token_is_first := true;
set_indent 0;
cst_indent := indent_spec;
try ignore(token lexbuf);
`Success (List.rev !line_indentations);
with Error (e,loc) -> `Failure (e,loc,(List.rev !line_indentations))