Add tutorial code

Author: martin-martin

python-web-applications/app.yaml

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+runtime: python38

python-web-applications/main.py

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+from flask import Flask
+from flask import request
+
+app = Flask(__name__)
+
+
+def convert_temp(cel_temp):
+    """Converts Celsius temperature to Fahrenheit temperature."""
+    try:
+        far_temp = float(cel_temp) * 9 / 5 + 32
+        far_temp = round(far_temp, 3)  # round to three decimal places
+        return str(far_temp)
+    except ValueError:  # user entered non-numeric temperature
+        return "invalid input"
+
+
+@app.route("/")
+def index():
+    cel_temp = request.args.get("cel_temp")
+    if cel_temp:
+        far_temp = convert_temp(cel_temp)
+    else:
+        far_temp = ""
+    return (
+        """<form action="">
+                Celsius: <input type="text" name="cel_temp">
+                <input type="submit" value="Convert">
+            </form>"""
+        + "Fahrenheit: "
+        + far_temp
+    )
+
+
+if __name__ == "__main__":
+    app.run(host="127.0.0.1", port=8080, debug=True)

python-web-applications/requirements.txt

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+flask