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