public SingleValueRowMapper(RoleMappedSchema schema, SchemaBindablePredictorWrapperBase parent, ISchema outputSchema)
            {
                Contracts.AssertValue(schema);
                Contracts.AssertValue(parent);
                Contracts.AssertValue(schema.Feature);
                Contracts.Assert(outputSchema.ColumnCount == 1);

                _parent       = parent;
                _inputSchema  = schema;
                _outputSchema = outputSchema;
            }