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Hello, In my application I use the etcd client API: [dependencies] etcd-client = "0.15.0" This defines: pub async fn put( &mut self, key: impl Into<Vec<u8>>, value: impl Into<Vec<u8>>, options: Option<PutOptions>, ) -> Result<PutResponse> { self.kv.put(key, value, options).await } I want to loop over a map of key/value pairs and call this method, but it complains that the client can only be borrowed mutably once. Here is the code I wrote: use std::vec; use etcd_client::{Client, Error}; use std::collections::HashMap; use futures; async fn create_keys() -> Result<(), Error> { let mut dict = HashMap::new(); dict.insert("k1", "vv1"); dict.insert("k2", "vv2"); dict.insert("k3", "vv3"); let mut client = Client::connect(["localhost:2379"], None).await?; let mut futures = vec![]; for (k,v) in dict.iter() { let fut = async { client.put(*k, *v, None).await; }; futures.push(fut); } futures::future::join_all(futures).await; Ok(()) } #[tokio::main] async fn main() -> Result<(), Error> { create_keys().await?; Ok(()) } Here is the problem description: error[E0499]: cannot borrow `client` as mutable more than once at a time --> mycrate/src/main.rs:15:19 | 15 | let fut = async { | ^^^^^ `client` was mutably borrowed here in the previous iteration of the loop 16 | client.put(*k, *v, None).await; | ------ borrows occur due to use of `client` in coroutine ... 20 | futures::future::join_all(futures).await; | ------- first borrow used here, in later iteration of loop For more information about this error, try `rustc --explain E0499`. error: could not compile `node` (bin "mycrate") due to 1 previous error I'm not sure how to use the API to do what I need. The key-value mappings I need to populate are not known at compile time (the hashmap is actually a surrogate for reading from a file) and I am quite new to Rust even (let alone async).

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