private void ParseVarDeclaration()
{
Match(TokenKind.Let);
_astBuilder.VarStmtStart(_scanner.CurrentToken);
Match(TokenKind.Let);
_scanner.Advance();
_astBuilder.VarStmtIdent(_scanner.CurrentToken);
Match(TokenKind.Identifier);
_scanner.Advance();
Match(TokenKind.Colon);
_scanner.Advance();
_astBuilder.VarStmtType(_scanner.CurrentToken);
ParseType();
Match(TokenKind.Assign);
_scanner.Advance();
ParseExpression();
_astBuilder.VarStmtEnd(_scanner.CurrentToken);
}