lib/lexer.js
function(file, prop) {
    return this.createNode(prop, file[prop], `{% ${prop} "${file[prop]}" %}`, this.position());
  }
function(file, prop) {
    return this.createNode(prop, file[prop], `{% ${prop} "${file[prop]}" %}`, this.position());
  }
Unshift node `prop` onto the AST