error[E0277]: the trait bound `i64: std::iter::Sum<std::result::Result<i64, std::num::ParseIntError>>` is not satisfied
 --> /in/foo.rs:9:25
  |
9 |                        .sum(); 
  |                         ^^^ the trait `std::iter::Sum<std::result::Result<i64, std::num::ParseIntError>>` is not implemented for `i64`
  |
  = help: the following implementations were found:
  = help:   <i64 as std::iter::Sum>
  = help:   <i64 as std::iter::Sum<&'a i64>>

error: aborting due to previous error