diff --git a/base/system_info.py b/base/system_info.py
index 64b4f39..433ec0f 100644
--- a/base/system_info.py
+++ b/base/system_info.py
@@ -78,7 +78,7 @@ SUPPORTED_PLATFORMS = [SupportedPlatform('linux', [Architecture('x86_64', 64, '/
                            Architecture('arm', 32, '/opt/android-ndk/platforms/android-9/arch-arm/usr/')], ['APK'])]
 
 
-def get_extension_by_package(package_type):
+def get_extension_by_package(package_type) -> str:
     if package_type == 'DEB':
         return 'deb'
     elif package_type == 'RPM':
@@ -97,7 +97,7 @@ def get_extension_by_package(package_type):
         return None
 
 
-def get_os():
+def get_os() -> str:
     uname_str = platform.system()
     if 'MINGW' in uname_str:
         return 'windows'
@@ -115,18 +115,18 @@ def get_os():
         return None
 
 
-def get_arch_name():
+def get_arch_name() -> str:
     arch = platform.machine()
     if arch == 'AMD64':
         return 'x86_64'
     return arch
 
 
-def get_supported_platform_by_name(platform):
+def get_supported_platform_by_name(platform) -> SupportedPlatform:
     return next((x for x in SUPPORTED_PLATFORMS if x.name() == platform), None)
 
 
-def gen_routing_key(platform, arch):
+def gen_routing_key(platform, arch) -> str:
     return platform + '_' + arch
 
 
@@ -151,5 +151,5 @@ SUPPORTED_BUILD_SYSTEMS = [BuildSystem('ninja', ['ninja'], '-GNinja'),
                            BuildSystem('gmake', ['gmake', '-j2'], '-GUnix Makefiles')]
 
 
-def get_supported_build_system_by_name(name):
+def get_supported_build_system_by_name(name) -> BuildSystem:
     return next((x for x in SUPPORTED_BUILD_SYSTEMS if x.name() == name), None)
diff --git a/base/utils.py b/base/utils.py
index 19b0e0f..880e1e9 100644
--- a/base/utils.py
+++ b/base/utils.py
@@ -2,13 +2,16 @@
 
 import os
 
+
 class BuildError(Exception):
     def __init__(self, value):
         self.value_ = value
+
     def __str__(self):
         return self.value_
 
-def read_file_line_by_line(file):
+
+def read_file_line_by_line(file) -> list:
     if not os.path.exists(file):
         raise BuildError('file path: %s not exists' % file)
 
@@ -17,4 +20,4 @@ def read_file_line_by_line(file):
         for line in ins:
             file_array.append(line.strip())
 
-    return file_array
\ No newline at end of file
+    return file_array