# Functions
EnsureMessage returns context and message, if there is a message in context, returns the original one, if not, returns a new one.
Message returns the message of context.
WithNewMessage creates a new empty message, retrieves it from the message pool, and associates it with the provided context.
# Constants
trpc context key data.
ServiceSectionLength is the length of service section, service name example: trpc.app.server.service.
# Interfaces
Msg defines core message data for Multi-protocol, business protocol should set this message when packing and unpacking data.
# Type aliases
CommonMeta is common meta message.
ContextKey is trpc context key type, the specific value is judged by interface, the interface will both judge value and type.
MetaData is request penetrate message.