'Return a list of the absolute paths for all fileids in this corpus;
or for the given list of fileids, if specified.
:type fileids: None or str or list
:param fileids: Specifies the set of fileids for which paths should
be returned.  Can be None, for all fileids; a list of
file identifiers, for a specified set of fileids; or a single
file identifier, for a single file.  Note that the return
value is always a list of paths, even if ``fileids`` is a
single file identifier.
:param include_encoding: If true, then return a list of
``(path_pointer, encoding)`` tuples.
:rtype: list(PathPointer)'

def abspaths(self, fileids=None, include_encoding=False, include_fileid=False):

    if (fileids is None):
        fileids = self._fileids
    elif isinstance(fileids, string_types):
        fileids = [fileids]
    paths = [self._root.join(f) for f in fileids]
    if (include_encoding and include_fileid):
        return list(zip(paths, [self.encoding(f) for f in fileids], fileids))
    elif include_fileid:
        return list(zip(paths, fileids))
    elif include_encoding:
        return list(zip(paths, [self.encoding(f) for f in fileids]))
    else:
        return paths
