Module wrappers

Wrappers around trace implementations, providing derived views of updates.

Modules

• enter
  Wrappers to provide trace access to nested scopes.
• enter_at
  Wrappers to provide trace access to nested scopes.
• filter
  Wrapper for filtered trace.
• freeze
  Wrappers to transform the timestamps of updates.
• frontier
  Wrapper for frontiered trace.
• rc
  A reference-counted wrapper sharing one owned trace.