More docstrings

Author: MilesCranmer

docs/src/utils.md

@@ -7,6 +7,7 @@ collection of its nodes.
 
 ```@docs
 copy(tree::AbstractExpressionNode; break_sharing::Val=Val(false))
+collect(tree::AbstractNode; break_sharing::Val=Val(false))
 filter(f::Function, tree::AbstractNode; break_sharing::Val=Val(false))
 count(f::Function, tree::AbstractNode; init=0, break_sharing::Val=Val(false))
 foreach(f::Function, tree::AbstractNode; break_sharing::Val=Val(false))

src/base.jl

@@ -294,6 +294,11 @@ function filter(f::F, tree::AbstractNode; break_sharing::Val=Val(false)) where {
     return filter_map(f, identity, tree, typeof(tree); break_sharing)
 end
 
+"""
+    collect(tree::AbstractNode; break_sharing::Val=Val(false))
+
+Collect all nodes in a tree into a flat array in depth-first order.
+"""
 function collect(tree::AbstractNode; break_sharing::Val=Val(false))
     return filter(Returns(true), tree; break_sharing)
 end