diff --git a/.github/workflows/python-package.yml b/.github/workflows/python-package.yml
index afa3be2..63151f7 100644
--- a/.github/workflows/python-package.yml
+++ b/.github/workflows/python-package.yml
@@ -15,17 +15,21 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       fail-fast: false
+      matrix:
+        python-version:
+          - "3.10"
+          - "3.11"
 
     steps:
-    - uses: actions/checkout@v2
-    - name: Set up Python 3.10-dev
-      uses: actions/setup-python@v2
+    - uses: actions/checkout@v3
+    - name: Set up Python ${{ matrix.python-version }}
+      uses: actions/setup-python@v2.3.1
       with:
-        python-version: "3.10-dev"
+        python-version: ${{ matrix.python-version }}
     - name: Install dependencies
       run: |
-        python3.10 -m pip install --upgrade pip
-        python3.10 -m pip install --upgrade pytest pytest-cov
+        pip install --upgrade pip
+        pip install --upgrade pytest pytest-cov
         if [ -f requirements.txt ]; then pip install -r requirements.txt; fi
 #     - name: Lint with flake8
 #       run: |
@@ -35,7 +39,7 @@ jobs:
 #         flake8 . --count --exit-zero --max-complexity=10 --max-line-length=127 --statistics
     - name: Test with pytest
       run: |
-        python3.10 -m pytest --cov=calculator tests/
+        pytest --cov=calculator tests/
     - name: Upload coverage to Codecov
       uses: codecov/codecov-action@v1
       with:
diff --git a/calculator/parser_.py b/calculator/parser_.py
index 737f219..8174e7d 100644
--- a/calculator/parser_.py
+++ b/calculator/parser_.py
@@ -7,7 +7,7 @@ class Parser:
         self.tokens = iter(tokens)
         self.advance()
 
-    def raise_error(self, e = None):
+    def raise_error(self, e=None):
         if e:
             raise Exception(f"Error: {e}")
         raise Exception("Invalid syntax")