Send not general error example

example.rs

pub struct ExampleClient { }

impl ExampleClient {    
    // calling .iter().map(|s| s.as_str()) on a Vec<String>
    // and passing it into the function with this signature causes a
    // compile error in poem_openapi's macro that compiles the server,
    // about Send's implementation not being general enough for &sqlx::Pool<_> and &ShardConfig,
    // saying they're only implemented for some &'0 T
    pub async fn get_with_str_iter<T>(
        &self,
        _a: &str,
        _b: impl IntoIterator<Item = &str>,
    ) -> Vec<T> {
        // real code calls out to redis using the strs as part of keys
        todo!()
    }

    // passing the same Vec<String> into this version of the function,
    // which otherwise does the exact same thing, works fine.
    pub async fn get_with_vec<T>(&self, _a: &str, _b: Vec<String>) -> Vec<T> {
        todo!()
    }

    // this one works when the first one failed, but not
    // without the where clause, which feels a bit redundant?
    pub async fn get_with_str_iter_new<'a, I: IntoIterator<Item = &'a str> + Send, T>(
        &self,
        _a: &str,
        _b: I,
    ) -> Vec<T>
    where
        <I as IntoIterator>::IntoIter: Send,
    {
        todo!()
    }
}