Macro execution_context::flow_local

macro_rules! flow_local {
    (static $NAME:ident : $t:ty = $e:expr) => { ... };
}

A macro to create a static of type FlowLocal

This macro is intentionally similar to the thread_local!, and creates a static which has a get_mut method to access the data on a flow.

The data associated with each flow local is per-flow, so different flows will contain different values.