Method parse_parameter

parser/src/parser/parser.rs:3239–3267

(
        &mut self,
        is_lambda: bool,
    )

    }

    fn parse_parameter(
        &mut self,
        is_lambda: bool,
    ) -> Result<(Arg, Option<Expression>), ParsingError> {
        let node = self.start_node();
        let arg = self.cur_token().to_string(self.source);
        self.bump(Kind::Identifier);
        // Lambda parameters cannot have annotations
        let annotation = if self.at(Kind::Colon) && !is_lambda {
            self.bump(Kind::Colon);
            Some(self.parse_expression()?)
        } else {
            None
        };
        let arg_node = self.finish_node(node);
        let default = if self.eat(Kind::Assign) {
            Some(self.parse_expression()?)
        } else {
            None
        };
        Ok((
            Arg {
                node: arg_node,
                arg,
                annotation,
            },
            default,
        ))
    }

    // the FStringStart token is consumed by the caller
    fn parse_fstring(&mut self, node: Node) -> Result<Vec<Expression>, ParsingError> {