This opens a file and returns a handle object, which can be used for methods that need an open file, such as alignment.read_one(). Many methods (such as model.write()) can also be given a writeable file handle, to have them append their output to that file rather than creating a new one. (They can also be given a Python filelike object, such as sys.stdout or io.StringIO, to write to a Python file; however, this is less efficient as it must call Python functions to do the IO.)
The file is closed automatically when the handle object is deleted, or explicitly by calling its close method.
The mode argument functions similarly to that used by C or Python; i.e., the following modes are acceptable: 'r', 'w', 'rb' and 'wb', to open a file for reading in text mode, writing in text mode, reading in binary mode, or writing in binary mode, respectively. Note that while only Windows operating systems make a distinction between text and binary mode, MODELLER will do some additional checks on text format files to catch common mistakes (e.g., trying to read a Unicode rather than plain text file) so you should use the 'b' suffix on all platforms if you are using binary files.Example: See alignment.read_one() command.