chunk_to_var_sym
left = chunk_to_var_sym(left_expr, &left_sym);
right = chunk_to_var_sym(right_expr, &right_sym);
left_name = chunk_to_var_sym(left, &left_sym);
right_name = chunk_to_var_sym(right, &right_sym);
left_var = chunk_to_var_sym(left, &left_sym);
right_var = chunk_to_var_sym(right, &right_sym);
left_var = chunk_to_var_sym(left, &left_sym);
right_var = chunk_to_var_sym(right, &right_sym);
return chunk_to_var_sym(expr, NULL);
name = chunk_to_var_sym(expr, &sym);
var = chunk_to_var_sym(expr, &sym);