<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 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