fn expect_peek_identifier(&mut self) -> ParseResult<String> {
        let name = match &self.peek_token.value {
            Token::Identifier(name) => name.to_owned(),
            _ => {
                return Err(ParseError::Expected(
                    String::from("identifier"),
                    self.peek_token.clone(),
                ))
            }
        };

        self.next_token()?;
        Ok(name)
    }
/// Expect the next (peek) token to be an identifier (get its name if so)
Expect the next (peek) token to be an identifier (get its name if so)
Expect the next ( peek ) token to be an identifier ( get its name if so )
fn expect_peek_identifier(&mut self) -> ParseResult<String> {
        let name = match &self.peek_token.value {
            Token::Identifier(name) => name.to_owned(),
            _ => {
                return Err(ParseError::Expected(
                    String::from("identifier"),
                    self.peek_token.clone(),
                ))
            }
        };
        self.next_token()?;
        Ok(name)
    }
fn expect_peek_identifier ( & mut self ) -> ParseResult < String > { let name = match & self . peek_token . value { Token :: Identifier ( name ) => name . to_owned ( ) , _ => { return Err ( ParseError :: Expected ( String :: from ( " " ) , self . peek_token . clone ( ) , ) ) } } ; self . next_token ( ) ? ; Ok ( name ) }
Expect the next (peek) token to be an identifier (get its name if so)
Expect the next ( peek ) token to be an identifier ( get its name if so )
&mut self