code: function build (data, cache, scope) {
  	scope = scope || { var: '' }
  
  	return data
  		.map(function (item) {
  			return typeof item === 'string'
  				? item
  					: Buffer.isBuffer(item)
  						? item.toString()
  						: item.run(cache, scope)
  		})
  		.join('')
  }
docs: Walk the AST and evaluate the nodes