Update examples to use asyncio event loop

The user had tried to instantiate the client outside the
asyncio event loop, but it must be created within the loop
to handle asynchronous calls correctly.

This change updates the examples to use async functions
and runs them within an asyncio event loop.

Signed-off-by: Daniel Zullo <[email protected]>

Author: daniel-zullo-frequenz

src/frequenz/client/electricity_trading/__init__.py

@@ -36,16 +36,21 @@
 ???+ example "Initialize the client"
 
     ```python
+    import asyncio
     from frequenz.client.electricity_trading import Client
 
     # Change server address if needed
     SERVICE_URL = "grpc://electricity-trading.api.frequenz.com:443?ssl=true"
     with open('/path/to/api_key.txt', 'r', encoding='utf-8') as f:
         API_KEY = f.read().strip()
-    client = Client(
-        server_url=SERVICE_URL,
-        auth_key=API_KEY
-    )
+
+    async def initialize():
+        client = Client(
+            server_url=SERVICE_URL,
+            auth_key=API_KEY
+        )
+
+    asyncio.run(initialize())
     ```
 
 ### Example Usage
@@ -58,6 +63,7 @@
 ???+ example "Create a limit order"
 
     ```python
+    import asyncio
     from frequenz.client.electricity_trading import (
         Client,
         Currency,
@@ -76,32 +82,36 @@
     SERVICE_URL = "grpc://electricity-trading.api.frequenz.com:443?ssl=true"
     with open('/path/to/api_key.txt', 'r', encoding='utf-8') as f:
         API_KEY = f.read().strip()
-    client = Client(
-        server_url=SERVICE_URL,
-        auth_key=API_KEY
-    )
 
-    # Define order parameters
-    GRIDPOOL_ID = 1
-    delivery_area = DeliveryArea(
-        code="10YDE-EON------1",  # TenneT
-        code_type=EnergyMarketCodeType.EUROPE_EIC
-    )
-    delivery_period = DeliveryPeriod(
-        start=datetime.fromisoformat("2024-05-01T00:00:00+00:00"),
-        duration=timedelta(minutes=15)
-    )
-    price = Price(amount=Decimal("50.0"), currency=Currency.EUR)
-    quantity = Energy(mwh=Decimal("0.1"))
-    order = await client.create_gridpool_order(
-        gridpool_id=GRIDPOOL_ID,
-        delivery_area=delivery_area,
-        delivery_period=delivery_period,
-        order_type=OrderType.LIMIT,
-        side=MarketSide.BUY,
-        price=price,
-        quantity=quantity,
-    )
+    async def create_order():
+        client = Client(
+            server_url=SERVICE_URL,
+            auth_key=API_KEY
+        )
+
+        # Define order parameters
+        gridpool_id = 1
+        delivery_area = DeliveryArea(
+            code="10YDE-EON------1",  # TenneT
+            code_type=EnergyMarketCodeType.EUROPE_EIC
+        )
+        delivery_period = DeliveryPeriod(
+            start=datetime.fromisoformat("2024-05-01T00:00:00+00:00"),
+            duration=timedelta(minutes=15)
+        )
+        price = Price(amount=Decimal("50.0"), currency=Currency.EUR)
+        quantity = Energy(mwh=Decimal("0.1"))
+        order = await client.create_gridpool_order(
+            gridpool_id=gridpool_id,
+            delivery_area=delivery_area,
+            delivery_period=delivery_period,
+            order_type=OrderType.LIMIT,
+            side=MarketSide.BUY,
+            price=price,
+            quantity=quantity,
+        )
+
+    asyncio.run(create_order())
     ```
 
 #### List Orders for a Gridpool
@@ -110,29 +120,34 @@
 ???+ example "List orders for a gridpool"
 
     ```python
+    import asyncio
     from frequenz.client.electricity_trading import ( Client, MarketSide )
 
     # Change server address if needed
     SERVICE_URL = "grpc://electricity-trading.api.frequenz.com:443?ssl=true"
     with open('/path/to/api_key.txt', 'r', encoding='utf-8') as f:
         API_KEY = f.read().strip()
-    client = Client(
-        server_url=SERVICE_URL,
-        auth_key=API_KEY
-    )
 
-    gridpool_id: int = 1
+    async def list_orders():
+        client = Client(
+            server_url=SERVICE_URL,
+            auth_key=API_KEY
+        )
 
-    # List all orders for a given gridpool
-    orders = await client.list_gridpool_orders(
-        gridpool_id=gridpool_id,
-    )
+        gridpool_id: int = 1
 
-    # List only the buy orders for a given gridpool
-    buy_orders = await client.list_gridpool_orders(
-        gridpool_id=gridpool_id,
-        side=MarketSide.BUY,
-    )
+        # List all orders for a given gridpool
+        orders = await client.list_gridpool_orders(
+            gridpool_id=gridpool_id,
+        )
+
+        # List only the buy orders for a given gridpool
+        buy_orders = await client.list_gridpool_orders(
+            gridpool_id=gridpool_id,
+            side=MarketSide.BUY,
+        )
+
+    asyncio.run(list_orders())
     ```
 
 
@@ -142,19 +157,24 @@
 
 ???+ example "Stream public trades"
     ```python
+    import asyncio
     from frequenz.client.electricity_trading import Client
 
     # Change server address if needed
     SERVICE_URL = "grpc://electricity-trading.api.frequenz.com:443?ssl=true"
     with open('/path/to/api_key.txt', 'r', encoding='utf-8') as f:
         API_KEY = f.read().strip()
-    client = Client(
-        server_url=SERVICE_URL,
-        auth_key=API_KEY
-    )
-    stream_public_trades = await client.stream_public_trades()
-    async for public_trade in stream_public_trades:
-        print(f"Received public trade: {public_trade}")
+
+    async def stream_trades():
+        client = Client(
+            server_url=SERVICE_URL,
+            auth_key=API_KEY
+        )
+        stream_public_trades = await client.stream_public_trades()
+        async for public_trade in stream_public_trades:
+            print(f"Received public trade: {public_trade}")
+
+    asyncio.run(stream_trades())
     ```
 
 """