docs: function parse(str) {
  
    // find the prefix expressions and the main value
    var stringMatches = str.match(stringRegex)
    var allExpString = stringMatches[1] || ''
    var value = stringMatches[2]
  
    // parse each prefix expression
    var expressions = execAll(allExpressionsRegex, allExpString)
      // grab the expression content inside the braces
      .map(function (match) { return match[1] })
      .map(parseExpression)
  
    return {
      original:   str,
      value:      value,
      expressions: expressions
    }
  }