Return XHTML content of a page.
    Parameters:
    - id: id of a Confluence page.

def get_page_content(id):
    """Return XHTML content of a page.
    Parameters:
    - id: id of a Confluence page.
    """
    data = _json.loads(_api.rest("/" + str(id) + "?expand=body.storage"))
    return data["body"]["storage"]["value"]