Opentelemetry_core.Span_ctxSpan context. This bundles up a trace ID and parent ID.
https://opentelemetry.io/docs/specs/otel/trace/api/#spancontext
val make :
?remote:bool ->
?sampled:bool ->
trace_id:Trace_id.t ->
parent_id:Span_id.t ->
unit ->
tval dummy : tInvalid span context, to be used as a placeholder
val is_remote : t -> boolDoes this come from a remote parent?
val is_valid : t -> boolAre the span ID and trace ID valid (ie non-zero)?
val trace_id : t -> Trace_id.tval sampled : t -> boolval to_w3c_trace_context : t -> bytesval of_w3c_trace_context_exn : bytes -> tHmap key to carry around a Span_ctx.t, e.g. to remember what the current parent span is.