pub trait NextArg {
// Required methods
fn next_arg(&mut self) -> Result<RedisString, RedisError>;
fn next_string(&mut self) -> Result<String, RedisError>;
fn next_str<'a>(&mut self) -> Result<&'a str, RedisError>;
fn next_i64(&mut self) -> Result<i64, RedisError>;
fn next_u64(&mut self) -> Result<u64, RedisError>;
fn next_f64(&mut self) -> Result<f64, RedisError>;
fn done(&mut self) -> Result<(), RedisError>;
}