why is there no del method for histogram types

[monkeyDluffy6017]

The counter and gauge has del method, however the histogram doesn't have one, how can i delete a particular metric that are histogram?

[knyar]

The primary reason is because deletion does not happen atomically, and deleting histogram counters will race with metric collection, potentially resulting in inconsistent data being scraped by prometheus, with some counters that are part of the histogram metric being present, but some already deleted.

I am open to contributions that aim to address this. Incrementing histogram counters is also racey with metric collection, which was the reason behind #161. If you have ideas on improving this and time to implement them, I'd be happy to discuss them and review the PR(s).