Refactoring and comments for the _fit method.
Refactoring and comments for the _fit method.


Former-commit-id: f83a8d30d99a5fd2f7636e3e147532897b0368a6 [formerly dfa96408432e7d401cd633074f5789fa11cd7a46]
Former-commit-id: c3c727a008d25860db3a6635e79f8a83ca65f86f
dpwolfe/otucha,dpwolfe/otucha,dpwolfe/otucha