diff --git a/.config/fish/conf.d/omf.fish b/.config/fish/conf.d/omf.fish
new file mode 100644
index 00000000..3e0f6d63
--- /dev/null
+++ b/.config/fish/conf.d/omf.fish
@@ -0,0 +1,7 @@
+# Path to Oh My Fish install.
+set -q XDG_DATA_HOME
+  and set -gx OMF_PATH "$XDG_DATA_HOME/omf"
+  or set -gx OMF_PATH "$HOME/.local/share/omf"
+
+# Load Oh My Fish configuration.
+source $OMF_PATH/init.fish
diff --git a/.config/fish/functions/concat.fish b/.config/fish/functions/concat.fish
new file mode 100644
index 00000000..4f2e0b34
--- /dev/null
+++ b/.config/fish/functions/concat.fish
@@ -0,0 +1,10 @@
+function concat
+	set delimiter $argv[1]
+	echo "delimiter->$delimiter"
+	set string ""
+	for x in $argv[2..-1]
+		set string "$string$delimiter$x"
+	end
+	echo $string
+end
+
diff --git a/useful_code/ruby/util/tree_printer.rb b/useful_code/ruby/util/tree_printer.rb
new file mode 100644
index 00000000..7f010813
--- /dev/null
+++ b/useful_code/ruby/util/tree_printer.rb
@@ -0,0 +1,49 @@
+module Util
+  class TreePrinter
+    attr_accessor :is_branch
+    attr_accessor :get_children
+    attr_accessor :format_node
+    attr_accessor :skip_root_node
+
+    def initialize
+      @arms = Hash.new("|   ")
+      @arms[""]  = ""
+      @arms["`"] = "    "
+      @out = ""
+      @is_branch    = proc{|node| node.has_children? }
+      @get_children = proc{|node| node.children}
+      @format_node  = proc{|node| node.to_s}
+      @skip_root_node = false
+    end
+    
+    def visit(path, leader, tie, arm, node)
+      if(@root == node) && skip_root_node
+        # skip
+      else
+        node_str = @format_node.call(node)
+        @out << "#{leader}#{arm}#{tie}#{node_str}\n"
+      end
+      visitChildren(node, leader + @arms[arm])
+      @out
+    end
+    
+    def visitChildren(path, leader)
+      kids = []
+      if(@root == path) && skip_root_node
+        kids = path
+      else
+        return unless @is_branch.call(path)
+        kids = @get_children.call(path)
+      end
+      return if kids.empty?
+      arms = Array.new(kids.length - 1, "|") << "`"
+      pairs = kids.zip(arms)
+      pairs.each { |e|  visit(path, leader, "-- ", e[1], e[0]) } 
+    end
+
+    def format(root)
+      @root = root
+      visit root, "", "", "", root 
+    end
+  end
+end