// Contract: TateWhales
// Target function: function add(Bytes4Set storage set, bytes4 value) internal returns (bool)
/**
 * 

Telegram : https://t.me/TateWhales

--TateWhales--

Welcome to TateWhales everyone! 

We proudly present: TateWhales

$TWHALES is a community-based 
ERC20 token with no transaction 
taxes. We took our cue from the 
successful Tate Family and combined it 
with the flavour of the month 
the hyped ‘TATE‘ meta.

Tog G to Rule Them All!
*/   
// SPDX-License-Identifier: AGPL-3.0-or-later
pragma solidity 0.7.5;

library EnumerableSet {

  // To implement this library for multiple types with as little code
  // repetition as possible, we write it in terms of a generic Set type with
  // bytes32 values.
  // The Set implementation uses private functions, and user-facing
  // implementations (such as AddressSet) are just wrappers around the
  // underlying Set.
  // This means that we can only create new EnumerableSets for types that fit
  // in bytes32.
  struct Set {
    // Storage of set values
    bytes32[] _values;

    // Position of the value in the `values` array, plus 1 because index 0
    // means a value is not in the set.
    mapping (bytes32 => uint256) _indexes;
  }

  /**
   * @dev Add a value to a set. O(1).
   *
   * Returns true if the value was added to the set, that is if it was not
   * already present.
   */
  function _add(Set storage set, bytes32 value) private returns (bool) {
    if (!_contains(set, value)) {
      set._values.push(value);
      // The value is stored at length-1, but we add 1 to all indexes
      // and use 0 as a sentinel value
      set._indexes[value] = set._values.length;
      return true;
    } else {
      return false;
    }
  }

  /**
   * @dev Removes a value from a set. O(1).
   *
   * Returns true if the value was removed from the set, that is if it was
   * present.
   */
  function _remove(Set storage set, bytes32 value) private returns (bool) {
    // We read and store the value's index to prevent multiple reads from the same storage slot
    uint256 valueIndex = set._indexes[value];

    if (valueIndex != 0) { // Equivalent to contains(set, value)
      // To delete an element from the _values array in O(1), we swap the element to delete with the last one in
      // the array, and then remove the last element (sometimes called as 'swap and pop').
      // This modifies the order of the array, as noted in {at}.

      uint256 toDeleteIndex = valueIndex - 1;
      uint256 lastIndex = set._values.length - 1;

      // When the value to delete is the last one, the swap operation is unnecessary. However, since this occurs
      // so rarely, we still do the swap anyway to avoid the gas cost of adding an 'if' statement.

      bytes32 lastvalue = set._values[lastIndex];

      // Move the last value to the index where the value to delete is
      set._values[toDeleteIndex] = lastvalue;
      // Update the index for the moved value
      set._indexes[lastvalue] = toDeleteIndex + 1; // All indexes are 1-based

      // Delete the slot where the moved value was stored
      set._values.pop();

      // Delete the index for the deleted slot
      delete set._indexes[value];

      return true;
    } else {
      return false;
    }
  }

  /**
   * @dev Returns true if the value is in the set. O(1).
   */
  function _contains(Set storage set, bytes32 value) private view returns (bool) {
    return set._indexes[value] != 0;
  }

  /**
   * @dev Returns the number of values on the set. O(1).
   */
  function _length(Set storage set) private view returns (uint256) {
    return set._values.length;
  }

   /**
    * @dev Returns the value stored at position `index` in the set. O(1).
    *
    * Note that there are no guarantees on the ordering of values inside the
    * array, and it may change when more values are added or removed.
    *
    * Requirements:
    *
    * - `index` must be strictly less than {length}.
    */
  function _at(Set storage set, uint256 index) private view returns (bytes32) {
    require(set._values.length > index, "EnumerableSet: index out of bounds");
    return set._values[index];
  }

  function _getValues( Set storage set_ ) private view returns ( bytes32[] storage ) {
    return set_._values;
  }

  // TODO needs insert function that maintains order.
  // TODO needs NatSpec documentation comment.
  /**
   * Inserts new value by moving existing value at provided index to end of array and setting provided value at provided index
   */
  function _insert(Set storage set_, uint256 index_, bytes32 valueToInsert_ ) private returns ( bool ) {
    require(  set_._values.length > index_ );
    require( !_contains( set_, valueToInsert_ ), "Remove value you wish to insert if you wish to reorder array." );
    bytes32 existingValue_ = _at( set_, index_ );
    set_._values[index_] = valueToInsert_;
    return _add( set_, existingValue_);
  } 

  struct Bytes4Set {
    Set _inner;
  }