var pe = require('postcss-pseudoelements');
var postcss = require('postcss');
var processor = postcss(pe({ selectors: ['before', 'after']}));
console.log(processor.process('a:before {}').css) // outputs: a:before {}
console.log(processor.process('a::before {}').css) // outputs: a:before {}selectors: Array of pseudo-element selectors to rewrite with single and double colons. Note that these values will be used in a regexp without escaping. Defaults to ['before','after']