Miguel Jimenez

The tests added for this PR use the following url: ```python http://test.opendap.org/opendap/hyrax/data/nc/test.nc?dap4.ce=/s33[0:][0:1:2];/br34[0:1:1][0:1:2][0:1:3];/s113[0:1:0][0:1:0][0:1:2] ```

Draft mode - some changes still necessary

### Description of state of this (active) PR After commit [ebefa0f](https://github.com/pydap/pydap/pull/310/commits/ebefa0f72447dc0bf1a665efe927c1fd42a60466), this now works (before it didn't): * **DAP2**: Sequences and constraint expressions: ```python $ url = "http://test.opendap.org/opendap/data/ff/1998.6.avhrr.dat" $ ds...

Thanks for your comments @jgallagher59701 . I agree with your overall assessment: stop at DAP4 + escaping of `[` `]` characters. When I started to work on this branch /...

@jgallagher59701 well finally this is ready for merger. I wrote an entire new pydap response utility that generates a DMR text so that pydap, oin theory, can server Group data....

sorry - that last commit was about reverting a change to a string representation in a test. But because the commit returns the string representation to what it used to...

**UPDATE** PR #310 fixes this issue.

> Passing `drop_variables` down to the backend seems like a good idea but will take some effort to implement across all backends. yeah, totally sound fair. > > Do you...

Thanks from my end too! I've been getting those and hadn't figured out a work around. Pretty random errors, and hard to reproduce!

> This is the code I am using to download data from a small region (with multiple Z levels) - https://gist.github.com/dhruvbalwada/0b1dc9c7002c278056f6e3320a45b9da . I had to switch to something where I...