ImportError while importing test module '/tmpfs/src/github/python-bigtable/tests/unit/test_row_merger.py'.
Hint: make sure your test modules/packages have valid Python names.
Traceback:
/usr/local/lib/python3.7/importlib/__init__.py:127: in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
tests/unit/test_row_merger.py:8: in 
    from google.cloud.bigtable.row_data import PartialRowsData, PartialRowData, InvalidChunk
google/cloud/bigtable/__init__.py:17: in 
    from google.cloud.bigtable.client import Client
google/cloud/bigtable/client.py:49: in 
    from google.cloud.bigtable.instance import Instance
google/cloud/bigtable/instance.py:21: in 
    from google.cloud.bigtable.table import Table
google/cloud/bigtable/table.py:30: in 
    from google.cloud._helpers import _to_bytes  # type: ignore
.nox/unit-3-7/lib/python3.7/site-packages/google/cloud/_helpers.py:28: in 
    import six
E   ModuleNotFoundError: No module named 'six'