To_yojson.Accumulator
type ('input_type, 'a, 'c) t = < to_json_accumulator : (string * ( 'input_type -> Yojson.Safe.t )) option list Core_kernel.ref.. > as 'a constraint ( 'input_type, 'a, 'c ) t = ( 'input_type, 'a, 'c ) Input.t