code: function(ast) {
      let value = this.value;
  
      ast.traverseByType('number', function(number) {
        if (!value) {
          number.content = number.content.replace(/^0+(?=\.)/, '');
        } else if (number.content[0] === '.') {
          number.content = '0' + number.content;
        }
      });
    }
docs: Processes tree node.
  @param {node} ast