**Use case**

```
CREATE TABLE t
(
    x UInt8,
    y UInt8,
)
```
{
    ParserKeyword s_index("INDEX");
    ParserKeyword s_constraint("CONSTRAINT");
    ParserKeyword s_projection("PROJECTION");
    ParserKeyword s_primary_key("PRIMARY KEY");
    ParserIndexDeclaration index_p;
    ParserConstraintDeclaration constraint_p;
    ParserProjectionDeclaration projection_p;
    ParserColumnDeclaration column_p{true, true};
    ParserExpression primary_key_p;
    ASTPtr new_node = nullptr;
    if (s_index.ignore(pos, expected))
    {
        if (!index_p.parse(pos, new_node, expected))
            return false;