Function protobuf::reflect::accessor::make_option_accessor

pub fn make_option_accessor<M, V>(
    name: &'static str, 
    get_field: fn<'a>(_: &'a M) -> &'a Option<V::Value>, 
    mut_field: fn<'a>(_: &'a mut M) -> &'a mut Option<V::Value>
) -> Box<FieldAccessor + 'static> where
    M: Message + 'static,
    V: ProtobufType + 'static,