def is_valid_file(ext, argument):
	""" Checks if file format is compatible """
	formats = {
		'input_pdb_path': ['pdb', 'pqr'],
		'input_clusters_zip': ['zip'],
        'resid_pdb_path': ['pdb'],
        'input_pdbqt_path': ['pdbqt'],
		'output_pdb_path': ['pdb'],
        'output_pdbqt_path': ['pdbqt']
	}
	return ext in formats[argument]