A function responsible for determining the percentage chance a given transaction (or service span in stream mode) will be sent to Sentry. This configuration option accepts a function, which takes one parameter (the sampling_context). The given sampling_context contains information about the transaction and the context in which it's being created. The function must return a number between 0 (0% chance of being sent) and 1 (100% chance of being sent). Can also be used for filtering transactions, by returning 0 for those that are unwanted.
Either this or traces_sample_rate must be defined to enable tracing.