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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 get_model_filepath(self, infodict):
 """Get the path to the homology model using information from the index dictionary for a single model. Example: use self.get_models(UNIPROT_ID) to get all the models, which returns a list of dictionaries. Use one of those dictionaries as input to this function to get the filepath to the model itself. Args: infodict (dict):
 Information about a model from get_models Returns: str: Path to homology model """

        u = infodict['uniprot_ac']

        original_filename = '{}_{}_{}_{}'.format(infodict['from'], infodict['to'],
                                                 infodict['template'], infodict['coordinate_id'])
        file_path = op.join(self.metadata_dir, u[:2], u[2:4], u[4:6],
                            'swissmodel', '{}.pdb'.format(original_filename))

        if op.exists(file_path):
            return file_path
        else:
            log.warning('{}: no file {} found for model'.format(u, file_path))
            return None