anchor.diff:  
   Attach custom contextual data to the current transaction and errors.
   Supported frameworks will automatically attach information about the HTTP request and the logged in user.
  -You can attach further data using this function. Example:
  +You can attach further data using this function.
  +
  +TIP: Before using custom context, ensure you understand the different types of
  +{apm-overview-ref-v}/metadata.html[metadata] that are available.
  +
  +Example:
   
   [source,python]
   ----
  
positive.code: ==== `elasticapm.tag()`
  
  Attach tags to the the current transaction and errors.
  Example:
  
  [source,python]
  
negative.code: following the `update()` semantics of Python dictionaries.
  
  The value is converted to a string.
  `.`, `*`, and `"` are invalid characters for tag names and will be replaced with `_`.
  
  WARNING: Avoid defining too many user-specified tags.
  Defining too many unique fields in an index is a condition that can lead to a
  {ref}/mapping.html#mapping-limit-settings[mapping explosion].
  