MH Objects
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`MH' instances have the following methods:
`error(format[, ...])'
Print an error message - can be overridden.
`getprofile(key)'
Return a profile entry (`None' if not set).
`getpath()'
Return the mailbox pathname.
`getcontext()'
Return the current folder name.
`setcontext(name)'
Set the current folder name.
`listfolders()'
Return a list of top-level folders.
`listallfolders()'
Return a list of all folders.
`listsubfolders(name)'
Return a list of direct subfolders of the given folder.
`listallsubfolders(name)'
Return a list of all subfolders of the given folder.
`makefolder(name)'
Create a new folder.
`deletefolder(name)'
Delete a folder - must have no subfolders.
`openfolder(name)'
Return a new open folder object.