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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def find_mof(self, classname):
 """ Find the MOF file that defines a particular CIM class, in the search path of the MOF compiler. The MOF file is found based on its file name: It is assumed that the base part of the file name is the CIM class name. Example: The class "CIM_ComputerSystem" is expected to be in a file "CIM_ComputerSystem.mof". Parameters: classame (:term:`string`):
 The name of the CIM class to look up. Returns: :term:`string`: Path name of the MOF file defining the CIM class, if it was found. `None`, if it was not found. """


        classname = classname.lower()
        for search in self.parser.search_paths:
            for root, dummy_dirs, files in os.walk(search):
                for file_ in files:
                    if file_.endswith('.mof') and \
                            file_[:-4].lower() == classname:
                        return os.path.join(root, file_)
        return None