/// Span metadata exposed as a dcontext value.
///
/// When [`DcontextLayer`](crate::DcontextLayer) is configured with
/// [`include_span_info()`](crate::DcontextLayerBuilder::include_span_info),
/// this type is automatically set in the context on span enter.
///
/// # Example
///
/// ```ignore
/// use dcontext_tracing::SpanInfo;
///
/// let info: SpanInfo = dcontext::sync_ctx::get_context("dcontext.span").unwrap_or_default();
/// println!("current span: {} ({})", info.name, info.target);
/// ```
/// The dcontext key used for [`SpanInfo`].
pub const SPAN_INFO_KEY: &str = "dcontext.span";