pub const OBJ_KEY_VALUE: &str = "value";
pub const OBJ_KEY_TYPE: &str = "type";
pub const OBJ_KEY_LANG: &str = "lang";
pub const OBJ_KEY_DATATYPE: &str = "datatype";
pub const OBJ_TYPE_BNODE: &str = "bnode";
pub const OBJ_TYPE_URI: &str = "uri";
pub const OBJ_TYPE_LITERAL: &str = "literal";
pub const BNODE_PREFIX: &str = "_:";