<commit_before>## v0.2.1 to-be-released

### Added

* `:combine` which merges multiple arrays into one using "join keys" (solnic)
* `:reject_key` which rejects specified keys in a hash (solnic)
* `:extract_key` converts the array of hashes to array of values (nepalez)

### Changed

* `Transproc.register` raises a meaningful error when a given function is already registered (kwando)
* `Transproc[]` raises a meaningful error when a given function doesn't exist (kwando)
* `Transproc[]` raises a meaningful error when a transformation crashes (kwando)

### Fixed

* `Transproc()` no longer creates a function if it's already a function (splattael)
* A couple of mistakes in the API docs (AMHOL)

### Internal<commit_msg>Update CHANGELOG [ci skip]<commit_after>## v0.2.1 to-be-released

### Added

* `:combine` which merges multiple arrays into one using "join keys" (solnic)
* `:reject_keys` which rejects specified keys in a hash (solnic)
* `:accept_keys` which accepts specified keys in a hash (solnic)
* `:extract_key` converts the array of hashes to array of values (nepalez)

### Changed

* `Transproc.register` raises a meaningful error when a given function is already registered (kwando)
* `Transproc[]` raises a meaningful error when a given function doesn't exist (kwando)
* `Transproc[]` raises a meaningful error when a transformation crashes (kwando)

### Fixed

* `Transproc()` no longer creates a function if it's already a function (splattael)
* A couple of mistakes in the API docs (AMHOL)

### Internal
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{'dir': 'git-commits-cleaned', 'id': '7503042', 'n_tokens_mistral': 461, 'n_tokens_neox': 438, 'n_words': 199}