code: function math (left, operator, right, options) {
    if (arguments.length < 3) {
      throw new Error('The "math" helper needs at least two arguments.');
    }
  
    if (options === undefined) {
      options = right;
      right = undefined;
    }
  
    left = parseFloat(left);
    right = parseFloat(right);
  
    if (operators[operator] === undefined) {
      throw new Error ('The "math" helper needs a valid operator.');
    }
  
    return operators[operator](left, right);
  }
docs: Perform mathematical operations on one or two values.
  
  @param {*} left
  @param {String} operator
  @param {*} right
  @param {Object} options
  @return {Number}
  @example:
  {{math 1 "+" 2}} //=> 3
  {{math 2 "-" 1}} //=> 1
  {{math 2 "*" 3}} //=> 6
  {{math 9 "/" 3}} //=> 3
  {{math 17 "%" 3}} //=> 2
  {{math 2 "**" 3}} //=> 8
  {{math 1 "++"}} //=> 2
  {{math 2 "--"}} //=> 1