Query String Parser

You're required to implement a type-level parser to parse URL query string into a object literal type.

Some detailed requirements:

• Value of a key in query string can be ignored but still be parsed to true. For example, 'key' is without value, so the parser result is { key: true }.
• Duplicated keys must be merged into one. If there are different values with the same key, values must be merged into a tuple type.
• When a key has only one value, that value can't be wrapped into a tuple type.
• If values with the same key appear more than once, it must be treated as once. For example, key=value&key=value must be treated as key=value only.