feat(generative-ai): Add function calling example for multimodal snippet (GoogleCloudPlatform#11015)

* Add function calling example for multimodal snippet

* Update generative_ai/function_calling.py

Co-authored-by: Sampath Kumar <[email protected]>

* Remove unused import

* 🦉 Updates from OwlBot post-processor

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md

---------

Co-authored-by: Sampath Kumar <[email protected]>
Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>

Author: 3 people

generative_ai/function_calling.py

@@ -0,0 +1,56 @@
+# Copyright 2023 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# [START aiplatform_function_calling]
+from vertexai.preview.generative_models import (
+    FunctionDeclaration,
+    GenerativeModel,
+    Tool,
+)
+
+# Load the Vertex AI Gemini API to use function calling
+model = GenerativeModel("gemini-pro")
+
+# Specify a function declaration and parameters for an API request
+get_current_weather_func = FunctionDeclaration(
+    name="get_current_weather",
+    description="Get the current weather in a given location",
+    # Function parameters are specified in OpenAPI JSON schema format
+    parameters={
+        "type": "object",
+        "properties": {"location": {"type": "string", "description": "Location"}},
+    },
+)
+
+# Define a tool that includes the above get_current_weather_func
+weather_tool = Tool(
+    function_declarations=[get_current_weather_func],
+)
+
+# Prompt to ask the model about weather, which will invoke the Tool
+prompt = "What is the weather like in Boston?"
+
+# Instruct the model to generate content using the Tool that you just created:
+response = model.generate_content(
+    prompt,
+    generation_config={"temperature": 0},
+    tools=[weather_tool],
+)
+
+# Print the entire response
+print(response)
+
+# Print the part of the response that contains info about the function call
+print(response.candidates[0].content.parts[0].function_call)
+# [END aiplatform_function_calling]