class WavelengthFitStatistics:
    @classmethod
    def readFits(cls, filename):
        """Read from file

        The method name says "readFits", but this doesn't actually need to be FITS.
        If the name bothers you, this can forward to a method with a better name.
        """
        # Read data from file, then:
        return cls(various, arguments)

    def writeFits(self, filename):
        """Write to file

        The method name says "writeFits", but this doesn't actually need to be FITS.
        If the name bothers you, this can forward to a method with a better name.
        """
        # Write data to file

price@MacBook:~/pfs/drp_stella (tickets/PIPE2D-380=) $ git sub
commit 7d064a37b3c867066c22cf476177f7a63ac2a5c1 (HEAD -> tickets/PIPE2D-380, origin/tickets/PIPE2D-380)
Author: Paul Price <price@astro.princeton.edu>
Date:   Wed May 22 20:26:45 2019 -0400

    save wavelength fit data
    
    A new class, WavelengthFitData, saves the wavelength fit data
    (centroid in pixels, fit wavelength, actual wavelength) for
    calculating statistics and for later QA.

 python/pfs/drp/stella/calibrateWavelengthsTask.py | 203 +++++++++++++++++++++-
 python/pfs/drp/stella/reduceArcTask.py            |   3 +-
 tests/test_WavelengthFitData.py                   | 117 +++++++++++++
 3 files changed, 321 insertions(+), 2 deletions(-)


price@MacBook:~/pfs/obs_pfs (tickets/PIPE2D-380=) $ git sub
commit 0a7c056a37ae247950063af9b45f78c5ac3b7edd (HEAD -> tickets/PIPE2D-380, origin/tickets/PIPE2D-380)
Author: Paul Price <price@astro.princeton.edu>
Date:   Wed May 22 15:38:28 2019 -0400

    PfsMapper: add wlFitData dataset
    
    For storing wavelength fit data.

 policy/PfsMapper.yaml | 10 ++++++++++
 1 file changed, 10 insertions(+)