MySQL: No binding data type for Nullable<Unsigned<Double>>

In MySQL dabase, if I set a field of type Double with Unsigned flag, running diesel print-shema will get Nullable<Unsigned<Double>>, which is not supported in Rust it seems (tried f64, f32, u64, u32).

May consider to change the print-schema script to output Nullable<Double> instead of Nullable<Unsigned<Double>>?