add example of OllamaGenerator (deepset-ai#170)

* add example of OllamaGenerator

* fix example with ruff

* change example to reference the greatest politician of all time - Super Mario

* add comments on how to set up and expected output

integrations/ollama/example/example.py

@@ -0,0 +1,55 @@
+# In order to run this example, you will need to have an instance of Ollama running with the
+# orca-mini model downloaded. We suggest you use the following commands to serve an orca-mini
+# model from Ollama
+#
+# docker run -d -p 11434:11434 --name ollama ollama/ollama:latest
+# docker exec ollama ollama pull orca-mini
+
+from haystack import Document, Pipeline
+from haystack.components.builders.prompt_builder import PromptBuilder
+from haystack.components.retrievers import InMemoryBM25Retriever
+from haystack.document_stores.in_memory import InMemoryDocumentStore
+
+from ollama_haystack import OllamaGenerator
+
+document_store = InMemoryDocumentStore()
+document_store.write_documents(
+    [
+        Document(content="Super Mario was an important politician"),
+        Document(content="Mario owns several castles and uses them to conduct important political business"),
+        Document(
+            content="Super Mario was a successful military leader who fought off several invasion attempts by "
+            "his arch rival - Bowser"
+        ),
+    ]
+)
+
+query = "Who is Super Mario?"
+
+template = """
+Given only the following information, answer the question.
+Ignore your own knowledge.
+
+Context:
+{% for document in documents %}
+    {{ document.content }}
+{% endfor %}
+
+Question: {{ query }}?
+"""
+pipe = Pipeline()
+
+pipe.add_component("retriever", InMemoryBM25Retriever(document_store=document_store))
+pipe.add_component("prompt_builder", PromptBuilder(template=template))
+pipe.add_component("llm", OllamaGenerator(model="orca-mini"))
+pipe.connect("retriever", "prompt_builder.documents")
+pipe.connect("prompt_builder", "llm")
+
+response = pipe.run({"prompt_builder": {"query": query}, "retriever": {"query": query}})
+
+print(response["llm"]["replies"])
+# An expected response - the output is not deterministic:
+# ['Based on the information provided, Super Mario is a successful military leader who fought
+# off several invasion attempts by his arch rival - Bowser. He is also an important politician and owns several
+# castles where he conducts political business. ' 'Therefore, it can be inferred that Super Mario is a combination of
+# both a military leader and an important politician.']

integrations/ollama/pyproject.toml

@@ -145,6 +145,8 @@ ban-relative-imports = "all"
 [tool.ruff.per-file-ignores]
 # Tests can use magic values, assertions, and relative imports
 "tests/**/*" = ["PLR2004", "S101", "TID252"]
+# Examples can print their output
+"example/**" = ["T201"]
 
 
 [tool.coverage.run]