The MultiFile object enables you to treat sections of a text
file as file-like input objects, with
'' being returned by
readline() when a given delimiter pattern is encountered. The
defaults of this class are designed to make it useful for parsing
MIME multipart messages, but by subclassing it and overriding methods
it can be easily adapted for more general use.
MultiFile only ever looks at the input object's readline(), seek() and tell() methods, and the latter two are only needed if you want random access to the individual MIME parts. To use MultiFile on a non-seekable stream object, set the optional seekable argument to false; this will prevent using the input object's seek() and tell() methods.
It will be useful to know that in MultiFile's view of the world, text is composed of three kinds of lines: data, section-dividers, and end-markers. MultiFile is designed to support parsing of messages that may have multiple nested message parts, each with its own pattern for section-divider and end-marker lines.