diff --git a/CHANGELOG.md b/CHANGELOG.md
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--- /dev/null
+++ b/CHANGELOG.md
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+# Changelog for gray-extended
+
+0.1.0.2 Package as flake.
+
+0.1.0.1 Reformatted source code.
+
+0.1.0.0 Initial release
diff --git a/LICENSE b/LICENSE
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--- /dev/null
+++ b/LICENSE
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+BSD 3-Clause License
+
+Copyright (c) 2022-2023 Amy de Buitléir
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+2. Redistributions in binary form must reproduce the above copyright notice,
+   this list of conditions and the following disclaimer in the documentation
+   and/or other materials provided with the distribution.
+
+3. Neither the name of the copyright holder nor the names of its
+   contributors may be used to endorse or promote products derived from
+   this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
diff --git a/SelectCode.hs b/SelectCode.hs
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+++ b/SelectCode.hs
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+{-# LANGUAGE OverloadedStrings #-}
+
+import qualified Text.Pandoc      as P
+import           Text.Pandoc.JSON (toJSONFilter)
+
+main :: IO ()
+main = toJSONFilter formatProofs
+
+formatProofs :: P.Block -> P.Block
+formatProofs x@(P.CodeBlock _ _) = x
+formatProofs _                   = P.Null
diff --git a/pandoc-select-code.cabal b/pandoc-select-code.cabal
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+++ b/pandoc-select-code.cabal
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+cabal-version:   3.0
+name:            pandoc-select-code
+version:         0.1.0.2
+synopsis:        Pandoc filter to extract only the code blocks.
+description:
+  For more information and a tutorial on how to use this package,
+  please see the README at <https://github.com/mhwombat/pandoc-select-code#readme>.
+homepage:        https://github.com/mhwombat/pandoc-select-code
+bug-reports:     https://github.com/mhwombat/pandoc-select-code/issues
+license:         BSD-3-Clause
+license-file:    LICENSE
+author:          Amy de Buitléir
+maintainer:      amy@nualeargais.ie
+copyright:       (c) 2020-2023 Amy de Buitléir
+category:        Text
+build-type:      Simple
+extra-doc-files: CHANGELOG.md
+
+executable pandoc-select-code
+  default-language: Haskell2010
+  default-extensions: ImportQualifiedPost
+  main-is:        SelectCode.hs
+  build-depends:
+    base >= 4.16.4 && < 4.17,
+    pandoc >= 2.19.2 && < 2.20,
+    pandoc-types >= 1.22.2 && < 1.23
+  ghc-options: -Wall -Wunused-packages