@pimms.param<EOL><INDENT>def transform(tx):<DEDENT>
if tx is None: return None<EOL>tx = to_affine(tx)<EOL>if np.array_equal(tx, np.eye(<NUM_LIT:3>)): return None<EOL>tx.setflags(write=False)<EOL>return tx<EOL>
mdl.transform is the matrix for the affine transform applied to the coordinates on the
cortical surface representation