issue_comments: 1122649316

Any pointers regarding where to start / modules involved to implement this? I would like to have a try.

The starting point would be to look at the code in indexing.py and try to understand how lazy indexing works.

In particular, look at

https://github.com/pydata/xarray/blob/3920c48d61d1f213a849bae51faa473b9c471946/xarray/core/indexing.py#L465-L470

Then you may want to try writing a class that looks like

```python class LazilyConcatenatedArray: # have to decide what to inherit from

def __init__(self, *arrays: LazilyIndexedArray, concat_axis=0):
    # figure out what you need to keep track of

@property
def shape(self):
    # figure out how to determine the total shape

def __getitem__(self, indexer) -> LazilyIndexedArray:
    # figure out how to map an indexer to the right piece of data

```