No tools for many index operations DArrays

From the http://dmlc.ml/MXNet.jl documentation as well as reading source code, the tools for comparison-based index operations on NDArrays are not apparent. Because NDArray is not compatible with common Julia index methods `find()`, etc the alternative is to write a method. However, there is no way to retrieve a conditional out of an NDArray, even an array of ones/zeros.

For example how would one find the index of the maximum element of an array? The `mx.maximum()` function returns the maximum element, and the `mx._equal()` function can do NDArray element-wise comparison. Thus, an NDArray of ones or a single element NDArray is found, but this can't be used as a Julia-compatible `Bool`.

This seems like a major flaw, and so it must be the case that I'm missing something simple here.

Edit:
`argmax()`, etc are in dlmc.ml documentation, but they throw errors:

`Check failed: mshadow::DataType::kFlag == type_flag_ TBlob.get_with_shape: data type do not match specified type.Expected: 6 v.s. given 0` ...

Edit2:
Found the `@mx.nd_as_jl` macro. If this is the only way to do index operations (i.e. while `argmax()`, etc are being fixed/implemented), then it should be highlighted more in documentation.