def read_markdown_file(file_path):
    """Reads a Markdown file and returns its content as a string.

    Args:
      file_path: The path to the Markdown file.

    Returns:
      The content of the file as a string, or an error message if the file
      cannot be read.
    """
    try:
        with open(file_path, 'r', encoding='utf-8') as file:
            content = file.read()
        return content
    except FileNotFoundError:
        return f"Error: The file at {file_path} was not found."
    except Exception as e:
        return f"An error occurred: {e}"


def replace_markdown_section_including_markers(filepath, start_marker, end_marker, new_content):
    """
    Replaces a section in a Markdown file, including the start and end markers themselves.

    Args:
        filepath (str): The path to the Markdown file.
        start_marker (str): The unique string marking the start of the section.
        end_marker (str): The unique string marking the end of the section.
        new_content (str): The new content to insert, which will replace the old section
                           and its markers.

    Returns:
        The modified content of the file as a string, or an error message if the file cannot be read.
    """
    try:
        with open(filepath, 'r', encoding='utf-8') as f:
            content = f.read()

        start_index = content.find(start_marker)
        if start_index == -1:
            print(f"Error: Start marker '{start_marker}' not found in the file.")
            return

        # Find the end marker starting from after the start marker's position
        # This prevents issues if the end marker appears before the start marker later in the file
        end_index = content.find(end_marker, start_index)
        if end_index == -1:
            print(f"Error: End marker '{end_marker}' not found after start marker in the file.")
            return

        # Calculate the actual end of the section to be replaced (inclusive of end_marker)
        section_end_inclusive = end_index + len(end_marker)

        # Construct the modified content
        modified_content = (
                content[:start_index] +  # Content before the start marker
                new_content +  # The new content replaces the entire old block
                content[section_end_inclusive:]  # Content after the end marker
        )

        return modified_content

    except FileNotFoundError:
        return f"Error: File '{filepath}' not found."
    except Exception as e:
        return f"An error occurred: {e}"