diff --git a/lib/binary_kata.ex b/lib/binary_kata.ex
index eb75fef..e345803 100644
--- a/lib/binary_kata.ex
+++ b/lib/binary_kata.ex
@@ -4,17 +4,20 @@ defmodule BinaryKata do
   Should return `true` when given parameter start with UTF8 Byte-Order-Mark, otherwise `false`.
   @see https://en.wikipedia.org/wiki/Byte_order_mark
   """
-  def has_utf8_bom?(_), do: raise "TODO: Implement me!"
+  def has_utf8_bom?(<<0xEF,0xBB,0xBF,_::binary>>), do: true
+  def has_utf8_bom?(_), do: false
 
   @doc """
   Remove a UTF8 BOM if exists.
   """
-  def remove_utf8_bom(_), do: raise "TODO: Implement me!"
+  def remove_utf8_bom(<<0xEF,0xBB,0xBF,rest::binary>>), do: rest
+  def remove_utf8_bom(<<rest::binary>>), do: rest
 
   @doc """
   Add a UTF8 BOM if not exists.
   """
-  def add_utf8_bom(_), do: raise "TODO: Implement me!"
+  def add_utf8_bom(all = <<0xEF,0xBB,0xBF,_::binary>>), do: all
+  def add_utf8_bom(all), do: <<0xEF,0xBB,0xBF>> <> all
 
   @doc """
   Detecting types of images by their first bytes / magic numbers.
@@ -23,7 +26,10 @@ defmodule BinaryKata do
   @see https://en.wikipedia.org/wiki/Portable_Network_Graphics
   @see https://en.wikipedia.org/wiki/GIF
   """
-  def image_type!(_), do: raise "TODO: Implement me!"
+  def image_type!("GIF" <> _), do: :gif
+  def image_type!(<<_::binary-size(6),"JFIF", _::binary>>), do: :jfif
+  def image_type!(<<_::binary-size(1),"PNG", _::binary>>), do: :png
+  def image_type!(_), do: :unknown
 
   @doc """
   Get the width and height from a GIF image.
@@ -32,15 +38,22 @@ defmodule BinaryKata do
   `width` will be little-endian in byte 7 and 8.
   `height` will be little-endian in byte 9 and 10.
   """
-  def gif_dimensions!(_), do: raise "TODO: Implement me!"
-
+  # def gif_dimensions!(<<_::binary-size(6), width::little-integer-size(2), height::little-integer-size(2), _::binary>>) do
+  #   {width, height}
+  # end
+  def gif_dimensions!(<<"GIF", _::binary-size(3), width::little-integer-size(16), height::little-integer-size(16), _::binary>>) do
+    {width, height}
+  end
+  def gif_dimensions!(_), do: :error
   @doc """
   Parsing Payload of a ARP packet. Padding will be omitted.
 
   @see https://en.wikipedia.org/wiki/Address_Resolution_Protocol
   """
-  def parse_arp_packet_ipv4!(_) do
-      raise "TODO: Implement me!"
+  def parse_arp_packet_ipv4!(<<_::binary-size(7), op::integer-size(8), sha::integer-size(48), spa::binary-size(4), tha::integer-size(48), tpa::binary-size(4), _::binary>>) do
+      <<a, b, c, d>> = spa
+      <<e, f, g, h>> = tpa
+      {arp_operation_to_atom(op), sha, {a, b, c, d}, tha, {e, f, g, h}}
   end
 
   # Helper for `parse_arp_packet_ipv4!`