Integrating MLUtils.DataLoader and image augmentation pipeline on custom dataset

Specific Domains Machine Learning
2

You likely need to import numobs

import MLUtils: numobs

or name it explicitly

MLUtils.numobs(data::my_dataset) = size(data.data_arr)[end]

By implementing it without importing or namespacing, you are defining a new function in the current module rather than adding a new method to the existing function.