Christmas Bird Count history report system

An instance of this class represents a logical row that displays the number of individuals for one kind of bird in each detail column, plus two cells of statistics. From the StatRow parent class it inherits the .suffixes() method that performs the statistical calculations.

# - - - - -   c l a s s   C e n s u s R o w

class CensusRow(StatRow):
    '''Represents counts of individuals for one kind of bird.

      Exports:
        CensusRow(cbcHist, birdId):
          [ (cbcHist is a CbcHist instance) and
            (birdId is an abbrMod.BirdId instance) ->
              return a new CensusRow instance for those values ]
        .addCensus(colx, census):
          [ (0 <= colx < self.cbcHist.nCols) and
            (census is a pycbc.Census instance) ->
              self  :=  self with the data from (census) added to
                        self's column [colx] ]
    '''