diff --git a/chatmastermind/message.py b/chatmastermind/message.py
new file mode 100644
index 0000000..db32b22
--- /dev/null
+++ b/chatmastermind/message.py
@@ -0,0 +1,55 @@
+"""
+Module implementing message related functions and classes.
+"""
+from typing import Type, TypeVar
+
+QuestionInst = TypeVar('QuestionInst', bound='Question')
+
+
+class MessageError(Exception):
+    pass
+
+
+def source_code(text: str, include_delims: bool = False) -> list[str]:
+    """
+    Extracts all source code sections from the given text, i. e. all lines
+    surrounded by lines tarting with '```'. If 'include_delims' is True,
+    the surrounding lines are included, otherwise they are omitted. The
+    result list contains every source code section as a single string.
+    The order in the list represents the order of the sections in the text.
+    """
+    code_sections: list[str] = []
+    code_lines: list[str] = []
+    in_code_block = False
+
+    print(text)
+
+    for line in text.split('\n'):
+        if line.strip().startswith("```"):
+            if include_delims:
+                code_lines.append(line)
+            if in_code_block:
+                code_sections.append("\n".join(code_lines))
+                code_lines.clear()
+                print(f" --> New code section:\n{code_sections}")
+            in_code_block = not in_code_block
+        elif in_code_block:
+            code_lines.append(line)
+
+    return code_sections
+
+
+class Question(str):
+    """
+    A single question with a defined prefix.
+    """
+    prefix = '=== QUESTION ==='
+
+    def __new__(cls: Type[QuestionInst], string: str) -> QuestionInst:
+        """
+        Make sure the question string does not contain the prefix.
+        """
+        if cls.prefix in string:
+            raise MessageError(f"Question '{string}' contains the prefix '{cls.prefix}'")
+        instance = super().__new__(cls, string)
+        return instance
diff --git a/tests/test_main.py b/tests/test_main.py
index eb13dc5..f99b015 100644
--- a/tests/test_main.py
+++ b/tests/test_main.py
@@ -8,6 +8,7 @@ from chatmastermind.api_client import ai
 from chatmastermind.configuration import Config
 from chatmastermind.storage import create_chat_hist, save_answers, dump_data
 from chatmastermind.tags import Tag, TagLine, TagError
+from chatmastermind.message import source_code
 from unittest import mock
 from unittest.mock import patch, MagicMock, Mock, ANY
 
@@ -345,3 +346,57 @@ class TestTagLine(CmmTestCase):
         # Test case 9: 'tags_or' and 'tags_and' are None, match all tags except excluded tags
         tags_not = {Tag('tag2')}
         self.assertFalse(tagline.match_tags(None, None, tags_not))
+
+
+class SourceCodeTestCase(CmmTestCase):
+    def test_source_code_with_include_delims(self) -> None:
+        text = """
+        Some text before the code block
+        ```python
+        print("Hello, World!")
+        ```
+        Some text after the code block
+        ```python
+        x = 10
+        y = 20
+        print(x + y)
+        ```
+        """
+        expected_result = [
+            "       ```python\n     print(\"Hello, World!\")\n      ```",
+            "       ```python\n     x = 10\n        y = 20\n        print(x + y)\n```"
+        ]
+        result = source_code(text, include_delims=True)
+        self.assertEqual(result, expected_result)
+
+    def test_source_code_without_include_delims(self) -> None:
+        text = """
+        Some text before the code block
+        ```python
+        print("Hello, World!")
+        ```
+        Some text after the code block
+        ```python
+        x = 10
+        y = 20
+        print(x + y)
+        ```
+        """
+        expected_result = [
+            "       print(\"Hello, World!\")\n",
+            "       x = 10\n        y = 20\n        print(x + y\n)"
+        ]
+        result = source_code(text, include_delims=False)
+        self.assertEqual(result, expected_result)
+
+    def test_source_code_with_single_code_block(self) -> None:
+        text = "```python\nprint(\"Hello, World!\")\n```"
+        expected_result = ["```python\nprint(\"Hello, World!\")\n```"]
+        result = source_code(text, include_delims=True)
+        self.assertEqual(result, expected_result)
+
+    def test_source_code_with_no_code_blocks(self) -> None:
+        text = "Some text without any code blocks"
+        expected_result: list[str] = []
+        result = source_code(text, include_delims=True)
+        self.assertEqual(result, expected_result)