diff --git a/.env b/.env
index e69de29..0e8a167 100644
--- a/.env
+++ b/.env
@@ -0,0 +1,5 @@
+PATCH_APPS=youtube,twitter,reddit,youtube_music
+BUILD_EXTENDED=True
+EXCLUDE_PATCH_YOUTUBE=custom-branding,enable-debugging
+EXCLUDE_PATCH_YOUTUBE_EXTENDED=custom-branding-red,custom-branding-blue,materialyou
+EXCLUDE_PATCH_YOUTUBE_MUSIC_EXTENDED=custom-branding-music
diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 422a7bc..c81fa8a 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -47,6 +47,12 @@ repos:
       - id: flake8
         args: [ "--config=setup.cfg" ]
 
+  - repo: https://github.com/pre-commit/mirrors-mypy
+    rev: v0.971
+    hooks:
+      - id: mypy
+        additional_dependencies: [ types-requests ]
+
 
 
 # sets up .pre-commit-ci.yaml to ensure pre-commit dependencies stay up to date
diff --git a/src/downloader.py b/src/downloader.py
index b25359a..5478897 100644
--- a/src/downloader.py
+++ b/src/downloader.py
@@ -143,7 +143,11 @@ class Downloader(object):
         main_page = parser.css_first(".appRowVariantTag>.accent_color").attributes[
             "href"
         ]
-        int_version = re.search(r"\d", main_page).start()
+        match = re.search(r"\d", main_page)
+        if not match:
+            logger.error("Cannot find app main page")
+            sys.exit(-1)
+        int_version = match.start()
         extra_release = main_page.rfind("release") - 1
         version = main_page[int_version:extra_release]
         version = version.replace("-", ".")
@@ -167,19 +171,19 @@ class Downloader(object):
         self._download(download_url, file_name=file_name)
 
     def download_revanced(self) -> None:
-        assets = (
-            ("revanced", "revanced-cli", self.normal_cli_jar),
-            ("revanced", "revanced-integrations", self.normal_integrations_apk),
-            ("revanced", "revanced-patches", self.normal_patches_jar),
-            ("inotia00", "VancedMicroG", "VancedMicroG.apk"),
-        )
+        assets = [
+            ["revanced", "revanced-cli", self.normal_cli_jar],
+            ["revanced", "revanced-integrations", self.normal_integrations_apk],
+            ["revanced", "revanced-patches", self.normal_patches_jar],
+            ["inotia00", "VancedMicroG", "VancedMicroG.apk"],
+        ]
         if self.build_extended:
-            assets += (
-                ("inotia00", "revanced-cli", self.cli_jar),
-                ("inotia00", "revanced-integrations", self.integrations_apk),
-                ("inotia00", "revanced-patches", self.patches_jar),
-            )
-        with ThreadPoolExecutor() as executor:
+            assets += [
+                ["inotia00", "revanced-cli", self.cli_jar],
+                ["inotia00", "revanced-integrations", self.integrations_apk],
+                ["inotia00", "revanced-patches", self.patches_jar],
+            ]
+        with ThreadPoolExecutor(7) as executor:
             executor.map(lambda repo: self.repository(*repo), assets)
         logger.info("Downloaded revanced microG ,cli, integrations and patches.")
 
diff --git a/src/parser.py b/src/parser.py
index 16c4bc0..88530e6 100644
--- a/src/parser.py
+++ b/src/parser.py
@@ -1,3 +1,4 @@
+import sys
 from subprocess import PIPE, Popen
 from time import perf_counter
 from typing import Any, List
@@ -6,9 +7,9 @@ from loguru import logger
 
 
 class Parser(object):
-    def __init__(self, patcher, env, temp_folder):
-        self._PATCHES = []
-        self._EXCLUDED = []
+    def __init__(self, patcher, env, temp_folder) -> None:
+        self._PATCHES: List[str] = []
+        self._EXCLUDED: List[str] = []
         self.patcher = patcher
         self.keystore_name = env.str("KEYSTORE_FILE_NAME", "revanced.keystore")
         self.build_extended = env.bool("BUILD_EXTENDED", False)
@@ -77,7 +78,11 @@ class Parser(object):
 
         start = perf_counter()
         process = Popen(["java", *args], stdout=PIPE)
-        for line in process.stdout:
+        output = process.stdout
+        if not output:
+            logger.error("Failed to send request for patching.")
+            sys.exit(-1)
+        for line in output:
             logger.debug(line.decode(), flush=True, end="")
         process.wait()
         logger.info(
diff --git a/src/patches.py b/src/patches.py
index 62a7871..974ea3d 100644
--- a/src/patches.py
+++ b/src/patches.py
@@ -11,8 +11,10 @@ from src.utils import supported_apps
 class Patches(object):
     def check_java(self) -> None:
         logger.debug("Checking if java is available")
-        jd = subprocess.check_output(["java", "-version"], stderr=subprocess.STDOUT)
-        jd = str(jd)[1:-1]
+        jd = subprocess.check_output(
+            ["java", "-version"], stderr=subprocess.STDOUT
+        ).decode("utf-8")
+        jd = jd[1:-1]
         if "Runtime Environment" not in jd:
             logger.debug("Java Must be installed")
             exit(-1)
@@ -91,7 +93,7 @@ class Patches(object):
         self.build_extended = env.bool("BUILD_EXTENDED", False)
         self.check_java()
         self.fetch_patches()
-        self.extended_apps = ["youtube", "youtube_music"]
+        self.extended_apps: List[str] = ["youtube", "youtube_music"]
 
     def get(self, app: str) -> Tuple[List[Dict[str, str]], str]:
         logger.debug("Getting patches for %s" % app)