sequence to replace do_parse

  macro_rules! sequence {
      ( { $($f:ident : $parser:expr;)* } => $output:expr ) => {
          move |i| {
              $(
                  let (i,$f) = $parser (i)?;
              )*
              Ok((i, $output))
          }
      };
  }

// example 
  fn one_or_two_lines(i: &str) -> IResult<&str,(&str,Option<&str>)> {
      sequence!(
          {
              a: terminated(take_until("\n"),tag("\n"));
              b: opt(take_until("\n"));
          } => (a,b)
      )(i)
  }