return the sheets of data.

def sheets(self):
        """return the sheets of data."""
        data = Dict()
        for src in [src for src in self.zipfile.namelist() if 'xl/worksheets/' in src]:
            name = os.path.splitext(os.path.basename(src))[0]
            xml = self.xml(src)
            data[name] = xml
        return data