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diff --git a/home-manager/firefox/unzip_mozlz4.py b/home-manager/firefox/unzip_mozlz4.py
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+#!/usr/bin/python
+# source: https://unix.stackexchange.com/a/497861
+# Command-line tool to decompress mozLz4 files used for example by Firefox to store various kinds of session backup information.
+# Works in both Python 2.7.15 and 3.6.7, as of version 2.1.6 of the LZ4 Python bindings at pypi.org/project/lz4.
+# To use in another script, simply cut and paste the import statement and the mozlz4_to_text() function (lines 8 to 17).
+
+import lz4.block  # pip install lz4 --user
+
+
+def mozlz4_to_text(filepath):
+    # Given the path to a "mozlz4", "jsonlz4", "baklz4" etc. file,
+    # return the uncompressed text.
+    bytestream = open(filepath, "rb")
+    bytestream.read(8)  # skip past the b"mozLz40\0" header
+    valid_bytes = bytestream.read()
+    text = lz4.block.decompress(valid_bytes)
+    return text
+
+
+def main(args):
+  # Given command-line arguments of an input filepath for a ".mozlz4" file
+  # and optionally an output filepath, write the decompressed text to the
+  # output filepath.
+  # Default output filepath is the input filepath minus the last three characters
+  # (e.g. "foo.jsonlz4" becomes "foo.json")
+  filepath_in = args[0]
+  if len(args) < 2:
+    filepath_out = filepath_in[:-3]
+  else:
+    filepath_out = args[1]
+  text = mozlz4_to_text(filepath_in)
+  with open(filepath_out, "wb") as outfile:
+    outfile.write(text)
+  print("Wrote decompressed text to {}".format(filepath_out))
+
+
+if __name__ == "__main__":
+  import sys
+  args = sys.argv[1:]
+  if args and not args[0] in ("--help", "-h"):
+    main(args)
+  else:
+    print("Usage: mozlz4.py <mozlz4 file to read> <location to write>")