Simplify refactorings

[marcpaterno]

This applies a few commits, each of which includes refactorings to simplify code. No changes of behavior are introduced.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 97.9%. Comparing base (de9d716) to head (aa39133).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #419 +/- ## ====================================== Coverage 97.9% 97.9% ====================================== Files 35 35 Lines 2974 2985 +11 ====================================== + Hits 2912 2923 +11 Misses 62 62 ``` | [Files](https://app.codecov.io/gh/LSSTDESC/firecrown/pull/419?dropdown=coverage&src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=LSSTDESC) | Coverage Δ | | |---|---|---| | [firecrown/\_\_init\_\_.py](https://app.codecov.io/gh/LSSTDESC/firecrown/pull/419?src=pr&el=tree&filepath=firecrown%2F__init__.py&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=LSSTDESC#diff-ZmlyZWNyb3duL19faW5pdF9fLnB5) | `100.0% <100.0%> (ø)` | | | [firecrown/connector/cosmosis/likelihood.py](https://app.codecov.io/gh/LSSTDESC/firecrown/pull/419?src=pr&el=tree&filepath=firecrown%2Fconnector%2Fcosmosis%2Flikelihood.py&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=LSSTDESC#diff-ZmlyZWNyb3duL2Nvbm5lY3Rvci9jb3Ntb3Npcy9saWtlbGlob29kLnB5) | `97.2% <100.0%> (+0.1%)` | :arrow_up: | | [firecrown/connector/mapping.py](https://app.codecov.io/gh/LSSTDESC/firecrown/pull/419?src=pr&el=tree&filepath=firecrown%2Fconnector%2Fmapping.py&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=LSSTDESC#diff-ZmlyZWNyb3duL2Nvbm5lY3Rvci9tYXBwaW5nLnB5) | `100.0% <100.0%> (ø)` | | | [firecrown/connector/numcosmo/numcosmo.py](https://app.codecov.io/gh/LSSTDESC/firecrown/pull/419?src=pr&el=tree&filepath=firecrown%2Fconnector%2Fnumcosmo%2Fnumcosmo.py&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=LSSTDESC#diff-ZmlyZWNyb3duL2Nvbm5lY3Rvci9udW1jb3Ntby9udW1jb3Ntby5weQ==) | `99.7% <100.0%> (ø)` | | | [firecrown/likelihood/gauss\_family/gauss\_family.py](https://app.codecov.io/gh/LSSTDESC/firecrown/pull/419?src=pr&el=tree&filepath=firecrown%2Flikelihood%2Fgauss_family%2Fgauss_family.py&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=LSSTDESC#diff-ZmlyZWNyb3duL2xpa2VsaWhvb2QvZ2F1c3NfZmFtaWx5L2dhdXNzX2ZhbWlseS5weQ==) | `99.3% <100.0%> (ø)` | | | [firecrown/likelihood/gauss\_family/gaussian.py](https://app.codecov.io/gh/LSSTDESC/firecrown/pull/419?src=pr&el=tree&filepath=firecrown%2Flikelihood%2Fgauss_family%2Fgaussian.py&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=LSSTDESC#diff-ZmlyZWNyb3duL2xpa2VsaWhvb2QvZ2F1c3NfZmFtaWx5L2dhdXNzaWFuLnB5) | `100.0% <100.0%> (ø)` | | | [...ood/gauss\_family/statistic/source/number\_counts.py](https://app.codecov.io/gh/LSSTDESC/firecrown/pull/419?src=pr&el=tree&filepath=firecrown%2Flikelihood%2Fgauss_family%2Fstatistic%2Fsource%2Fnumber_counts.py&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=LSSTDESC#diff-ZmlyZWNyb3duL2xpa2VsaWhvb2QvZ2F1c3NfZmFtaWx5L3N0YXRpc3RpYy9zb3VyY2UvbnVtYmVyX2NvdW50cy5weQ==) | `83.8% <100.0%> (ø)` | | | [...likelihood/gauss\_family/statistic/source/source.py](https://app.codecov.io/gh/LSSTDESC/firecrown/pull/419?src=pr&el=tree&filepath=firecrown%2Flikelihood%2Fgauss_family%2Fstatistic%2Fsource%2Fsource.py&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=LSSTDESC#diff-ZmlyZWNyb3duL2xpa2VsaWhvb2QvZ2F1c3NfZmFtaWx5L3N0YXRpc3RpYy9zb3VyY2Uvc291cmNlLnB5) | `100.0% <100.0%> (ø)` | | | [...hood/gauss\_family/statistic/source/weak\_lensing.py](https://app.codecov.io/gh/LSSTDESC/firecrown/pull/419?src=pr&el=tree&filepath=firecrown%2Flikelihood%2Fgauss_family%2Fstatistic%2Fsource%2Fweak_lensing.py&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=LSSTDESC#diff-ZmlyZWNyb3duL2xpa2VsaWhvb2QvZ2F1c3NfZmFtaWx5L3N0YXRpc3RpYy9zb3VyY2Uvd2Vha19sZW5zaW5nLnB5) | `92.7% <100.0%> (ø)` | | | [...own/likelihood/gauss\_family/statistic/supernova.py](https://app.codecov.io/gh/LSSTDESC/firecrown/pull/419?src=pr&el=tree&filepath=firecrown%2Flikelihood%2Fgauss_family%2Fstatistic%2Fsupernova.py&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=LSSTDESC#diff-ZmlyZWNyb3duL2xpa2VsaWhvb2QvZ2F1c3NfZmFtaWx5L3N0YXRpc3RpYy9zdXBlcm5vdmEucHk=) | `100.0% <100.0%> (ø)` | | | ... and [6 more](https://app.codecov.io/gh/LSSTDESC/firecrown/pull/419?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=LSSTDESC) | |