DOC Fixes grammar in decision tree's cpp pruning docstring
@@ -1458,9 +1458,10 @@ cdef _cost_complexity_prune(unsigned char[:] leaves_in_subtree, # OUT
"""Perform cost complexity pruning.
This function takes an already grown tree, `orig_tree` and outputs a
- boolean mask `leaves_in_subtree` to are the leaves in the pruned tree. The
- controller signals when the pruning should stop and is passed the
- metrics of the subtrees during the pruning process.
+ boolean mask `leaves_in_subtree` which are the leaves in the pruned tree.
+ During the pruning process, the controller is passed the effective alpha and
+ the subtree impurities. Furthermore, the controller signals when to stop
+ pruning.
Parameters
----------
