code: function includesSize(sizeArray, size) {
    if (isValidSize(sizeArray)) {
      return sizeArray[0] === size[0] && sizeArray[1] === size[1];
    }
  
    for (let i = 0; i < sizeArray.length; i++) {
      if (sizeArray[i][0] === size[0] && sizeArray[i][1] === size[1]) {
        return true;
      }
    }
  
    return false;
  }
docs: Determines whether or not the given size object is an element of the size
  array.
  
  @param  {array}  sizeArray The size array.
  @param  {object} size      The size object.
  @return {boolean}          True if the size object is an element of the size array, and false
  otherwise.