Macro begin_scope 

macro_rules! begin_scope {
    ($category:tt, $label:tt $(, $key:tt => $val:expr)* $(,)?) => { ... };
}

Creates a delegate to capture the given arguments at the beginning of a scope when the given category is enabled. The returned value should be used to construct a ktrace::Scope to track the lifetime of the scope and emit the complete trace event. The complete event is associated with the current thread.

Arguments:

• category: Filter category for the event. Expects a string literal or expression.
• label: Label for the event. Expects a string literal or expression.
• …: List of key => value argument pairs.