pub fn is_string(&self) -> bool {
        match *self {
            Value::String(_) => true,
            _ => false,
        }
    }
/// `is_string` returns true if the value is a string.
`is_string` returns true if the value is a string.
` is_string ` returns true if the value is a string .
pub fn is_string(&self) -> bool {
        match *self {
            Value::String(_) => true,
            _ => false,
        }
    }
pub fn is_string ( & self ) -> bool { match * self { Value :: String ( _ ) => true , _ => false , } }
`is_string` returns true if the value is a string.
` is_string ` returns true if the value is a string .
&self