Update trie docs

Author: jonas-schulze

docs/src/trie.md

@@ -1,40 +1,85 @@
+```@meta
+DocTestSetup = :(using DataStructures)
+```
+
 # Trie
 
 An implementation of the Trie data structure. This is an associative
-structure, with AbstractString keys:
+structure, with iterable keys:
 
-```julia
-t = Trie{Int}()
-t["Rob"] = 42
-t["Roger"] = 24
-haskey(t, "Rob")  # true
-get(t, "Rob", nothing)  # 42
-keys(t)  # "Rob", "Roger"
-keys(subtrie(t, "Ro"))  # "b", "ger"
+```jldoctest
+julia> t = Trie{Char,Int}();
+
+
+julia> t["Rob"] = 42;
+
+
+julia> t["Roger"] = 24;
+
+
+julia> haskey(t, "Rob")
+true
+
+julia> get(t, "Rob", nothing)
+42
+
+julia> keys(t)
+2-element Vector{String}:
+ "Roger"
+ "Rob"
+
+julia> keys(subtrie(t, "Ro"))
+2-element Vector{String}:
+ "ger"
+ "b"
+```
+
+Note that the keys don't need to be `String`s:
+
+```jldoctest
+julia> t = Trie{Int,Char}();
+
+julia> t[1:3] = 'a';
+
+julia> t[[2,3,5]] = 'b';
+
+julia> keys(t)
+2-element Vector{Vector{Int64}}:
+ [2, 3, 5]
+ [1, 2, 3]
 ```
 
 Constructors:
 
 ```julia
 Trie(keys, values)                  # construct a Trie with the given keys and values
-Trie(keys)                          # construct a Trie{Void} with the given keys and with values = nothing
+Trie(keys)                          # construct a Trie{K,Nothing} with the given keys and with values = nothing
 Trie(kvs::AbstractVector{(K, V)})   # construct a Trie from the given vector of (key, value) pairs
 Trie(kvs::AbstractDict{K, V})       # construct a Trie from the given associative structure
 ```
 
-This package also provides an iterator `partial_path(t::Trie, str)` for looping
-over all the nodes encountered in searching for the given string `str`.
+This package also provides an iterator `partial_path(t::Trie, prefix)` for looping
+over all the nodes encountered in searching for the given `prefix`.
 This obviates much of the boilerplate code needed in writing many trie
 algorithms. For example, to test whether a trie contains any prefix of a
-given string, use:
+given string `str`, use:
 
 ```julia
 seen_prefix(t::Trie, str) = any(v -> v.is_key, partial_path(t, str))
 ```
 
 `find_prefixes` can be used to find all keys which are prefixes of the given string.
 
-```julia
-t = Trie(["A", "ABC", "ABCD", "BCE"])
-find_prefixes(t, "ABCDE") # "A", "ABC", "ABCD"
-```
+```jldoctest
+julia> t = Trie(["A", "ABC", "ABCD", "BCE"]);
+
+julia> find_prefixes(t, "ABCDE")
+3-element Vector{String}:
+ "A"
+ "ABC"
+ "ABCD"
+```
+
+```@meta
+DocTestSetup = nothing
+```