use std::convert::TryFrom;


struct CourseResult {
    // a complex struct
    // with lots of Option<T>
    description: Option<String>
}

struct Ttem {
    // another complex struct
}

#[derive(Debug)]
struct ItemCreationError<'a> {
    msg: &'a str,
}

impl<'a> TryFrom<&'a CourseResult> for Item {
    type Error = ItemCreationError<'a>;
    fn try_from(course: &CourseResult) -> Result<Self, Self::Error> {
        let _desc = course.description.ok_or(ItemCreationError { msg: "AAAHHH" })?;
    }
}

fn main() {
    let courses : CourseResult = ....,
    let item = Item::try_from(courses);
}