WARNING on line 2, column 12 of spec/libsass-issues/issue_1418/dynamic-4.0/input.scss: 
DEPRECATION WARNING: Passing a string to call() is deprecated and will be illegal
in Sass 4.0. Use call(get-function(missing)) instead.
    color: call(missing, $a: b);
           ^^^^^^^^^^^^^^^^^^^^

Error: Plain CSS functions don't support keyword arguments.
    color: call(missing, $a: b);
           ^^^^^^^^^^^^^^^^^^^^
  spec/libsass-issues/issue_1418/dynamic-4.0/input.scss 2:12  root stylesheet
