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Controlling breakpoints and the amount of output

Some errors are recoverable. For those errors, a Python exception exception is raised. It is then up to your script to deal sensibly with the failure of the preceding command using a standard `'except'` clause. For example, this flexibility allows derivation of multiple models and searching for many sequences, even if some cases abort due to convergence problems. This exception could be a generic `ModellerError` exception, a more specific subclass (`FileFormatError`), or a standard Python exception5.1.

There are five kinds of messages that MODELLER writes to the `log` file: long output from the MODELLER commands, short notes to do with the execution of the program (files opened, etc.), warnings identified by `‘_W>’`, errors identified by `‘_E>’`, and the messages about the status of dynamic memory allocation. To control how much of this output is displayed, use the `log` object; for more information, see Section 6.31.