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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 process_forcefield(*forcefields):
 """ Given a list of filenames, check which ones are `frcmods`. If so, convert them to ffxml. Else, just return them. """

    for forcefield in forcefields:
        if forcefield.endswith('.frcmod'):
            gaffmol2 = os.path.splitext(forcefield)[0] + '.gaff.mol2'
            yield create_ffxml_file([gaffmol2], [forcefield])
        else:
            yield forcefield