code: function processArray (arr, reqStack) {
    const accum = []
    arr.forEach(function (el) {
      accum.push(schemaForm(el, reqStack))
    })
    return accum
  }
docs: Call `schemaForm` for each element of array.
  
  @param  {Array} arr
  @param  {Array} reqStack - Stack of required properties.
  @returns  {Array}