Returns the long_description_content_type based on the extension of the
    package describe path (e.g. .txt, .rst, or .md).

def get_description_type(path=PKG_DESCRIBE):
    """
    Returns the long_description_content_type based on the extension of the
    package describe path (e.g. .txt, .rst, or .md).
    """
    _, ext = os.path.splitext(path)
    return {
        ".rst": "text/x-rst",
        ".txt": "text/plain",
        ".md": "text/markdown",
    }[ext]