diff --git a/lib/binary_kata.ex b/lib/binary_kata.ex
index eb75fef..c4d51f1 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, _rest::binary >>), do: true
+  def has_utf8_bom?(<< _nope::binary >>), 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(<< all::binary >>), do: all
 
   @doc """
   Add a UTF8 BOM if not exists.
   """
-  def add_utf8_bom(_), do: raise "TODO: Implement me!"
+  def add_utf8_bom(<< 0xEF, 0xBB, 0xBF, rest::binary >>), do: << 0xEF, 0xBB, 0xBF >> <> rest
+  def add_utf8_bom(<< all::binary >>), 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!(<< 0xFF, 0xD8, 0xFF, _rest::binary >>), do: :jpeg
+  def image_type!(<< 0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A, _rest::binary >>), do: :png
+  def image_type!(<< 0x47, 0x49, 0x46, 0x38, _rest::binary >>), do: :gif
+  def image_type!(_), do: :unknown
 
   @doc """
   Get the width and height from a GIF image.
@@ -32,19 +38,44 @@ 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!(<< 0x47, 0x49, 0x46, 0x38, _, _, width::little-integer-size(16), height::little-integer-size(16), _rest::binary >>), do: {width, height}
+  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!(<<_head::48,
+                              1::16,
+                              sender_mac::integer-size(48),
+                              sender_ip_1::integer-size(8),
+                              sender_ip_2::integer-size(8),
+                              sender_ip_3::integer-size(8),
+                              sender_ip_4::integer-size(8),
+                              target_mac::integer-size(48),
+                              target_ip_1::integer-size(8),
+                              target_ip_2::integer-size(8),
+                              target_ip_3::integer-size(8),
+                              target_ip_4::integer-size(8),
+                              _rest::binary >>) do
+      {:request, sender_mac, {sender_ip_1, sender_ip_2, sender_ip_3, sender_ip_4}, target_mac, {target_ip_1, target_ip_2, target_ip_3, target_ip_4}}
   end
 
-  # Helper for `parse_arp_packet_ipv4!`
-  defp arp_operation_to_atom(1), do: :request
-  defp arp_operation_to_atom(2), do: :response
+  def parse_arp_packet_ipv4!(<<_head::48,
+                              2::16,
+                              sender_mac::integer-size(48),
+                              sender_ip_1::integer-size(8),
+                              sender_ip_2::integer-size(8),
+                              sender_ip_3::integer-size(8),
+                              sender_ip_4::integer-size(8),
+                              target_mac::integer-size(48),
+                              target_ip_1::integer-size(8),
+                              target_ip_2::integer-size(8),
+                              target_ip_3::integer-size(8),
+                              target_ip_4::integer-size(8),
+                              _rest::binary >>) do
+      {:response, sender_mac, {sender_ip_1, sender_ip_2, sender_ip_3, sender_ip_4}, target_mac, {target_ip_1, target_ip_2, target_ip_3, target_ip_4}}
+  end
 
 end
diff --git a/test/binary_kata_test.exs b/test/binary_kata_test.exs
index 78c588e..7bee850 100644
--- a/test/binary_kata_test.exs
+++ b/test/binary_kata_test.exs
@@ -18,7 +18,7 @@ defmodule BinaryKataTest do
   end
 
   test "image_type!" do
-    assert :jfif == fixture_file("image.jpg") |> BinaryKata.image_type!
+    assert :jpeg == fixture_file("image.jpg") |> BinaryKata.image_type!
     assert :png == fixture_file("image.png") |>  BinaryKata.image_type!
     assert :gif == fixture_file("image.gif") |> BinaryKata.image_type!
     assert :unknown == "something else" |> BinaryKata.image_type!