$ rebar3 compile

```erlang
1> {ok, Module} = sqlc:string(example, "
    query by_id(:id uuid) returns user as
        select user_id as id, name, avatar_url, created_at
            from example.user
            where user_id = :id;
").
{ok,{codegen,example,
            [{by_id,1}],
            [{by_id,[{tree,clause,
                            {attr,87,[],none},
                            {clause,[{tree,map_expr,
                                        {attr,0,[],none},
                                        {map_expr,none,[{tree,map_field_exact,{attr,...},{...}}]}}],
                                    none,
                                    [{tree,map_expr,
                                        {attr,88,[],none},
                                        {map_expr,none,
                                                    [{tree,map_field_assoc,...},{tree,...}]}}]}}]}]}}
2> io:format("~s~n", [sqlc_module:to_erl(Module)]).
%% @private
-module(example).

-export([by_id/1]).

by_id(#{id := Id}) ->
    #{type => query,
    statement =>
        [<<"select user_id as id, name, avatar_url, created_at\n "
            "   from example.user\n    where user_id = ">>,
        <<"(">>,
        {parameter, #{key => {example, by_id, id}, value => Id}},
        <<"::", "uuid">>,
        <<")">>]}.
ok
```