* corret type clause
* add tests, changes in create_json_string
* create json-string now gives back None
* revert changes
* fix panda sql export
* add SQL test
* fixed None type export for csv and sql.gz
* move None parsing to json io
* alter regex
* revert changes
* only replace None with empty str when necessary
* fixed deserialze_df for python 3.7
* add more tesets
* fix case where gz was ignored
* hand voer gz explicitly
* replace nan by None in non-Obs columns
* moved warning to csv export, mroe tests
* only values able to be nan are put in np.isnan()
* added python float for warning
* feat: Added serialization of list of Obs in pandas.to_sql.
* tests: test for list of Obs to sql added.
* feat: auto_gamma functionality added for deserialization of lists of
Obs.
* first example of returns statement in docstring
* added a some return statements for pandas API
* last return statements in pandas input
* added returns to bdio docstrings
* few returns statements added to docstring
* finished docstrings for hadrons submodule
* also finished docstrings for json submodule
* finished misc submodule
* added returns in docstrings in openqQCD
* made some cosmetic chanes to dostrings
* added return nad return statement in docstring
* linting
* Improved docstrings of mpm, fits, roots, misc to have return statements
returns added for misc.py
returns added for mpm.py
reutrns added for fits.py
* linting...
* Some polishing of docstrings
