Basic validation for a board

tictactoe.py

@@ -1,7 +1,23 @@
-from flask import Flask
+from flask import Flask, abort, request
 
 app = Flask(__name__)
 
 @app.route('/')
 def hello():
-    return 'Hello!'
+    board = _get_board_or_abort()
+    return board
+
+def _get_board_or_abort():
+    '''
+    Get the board from the request, or abort the request with a 400 error.
+    '''
+    board = request.args.get('board', None)
+    is_valid = all(
+        board is not None,  # 'board' var must exist.
+        len(board) >= 9,    # Board should be at least 9 characters long.
+    )
+
+    if not is_valid:
+        abort(400)
+
+    return board