// <Statement> ::= "PRODNAME" "::=" <Expression> "." .
private void ParseStatement()
{
ParseAction();
_astBuilder.BeginStatement(_scanner.CurrentToken);
Match(TokenKind.Identifier);
_scanner.Advance();
Match(TokenKind.Assign);
_scanner.Advance();
ParseExpression();
Match(TokenKind.Period);
_scanner.Advance();
ParseAction();
_astBuilder.EndStatement();
}