Switching between PC Storages 1.0

#============================================================
#Pokémon Storage Switch script by leilou
#
#For Essentials 17.2; Version 1.0
#
#This script is ment to make it easy to alternate between storage systems
#
#Pokémon Essentials is created by Poccil, based on Flameguru's
#Pokémon Starter Kit and managed and updated by Maruno
#
#I don't claim this script to be perfect.
#Please report bugs at the resources thread on Relic Castle.
#=============================================================

#Slot in $game_variables that is used for this.
#Make sure to set this to game variables not used in any other way!
STORAGE_GAME_VARIABLE_USED = 51

#this function saves the current storage int slot storageNumberPrevious
#and loads the storage in slot storageNumberNext into the current storage
#if this is the first time calling that storage a new empty storage will be made
#   and set as the current storage
#storageNumberPrevious    Integer   The ID Number the current storage will be saved in.
#storageNumberNext        Integer   The ID Number of the storage that will be loaded.
#                                   A new storage will be initialized if there is no save with that ID.
#                         nil       If a new storage is to be made.
#returns true on success and false on failure
def pbSwitchStorage(storageNumberPrevious, storageNumberNext)
  #checks for invalid inputs
  if !$game_variables
    return false
  end
  if (storageNumberPrevious == storageNumberNext)
    return false
  end
  if (!storageNumberPrevious.is_a? Integer ||
      !(storageNumberNext.is_a? Integer || storageNumberNext.nil?))
    return false
  end
 
  #initialize game variable if not already happened:
  if !$game_variables[STORAGE_GAME_VARIABLE_USED].kind_of?(Array)
    $game_variables[STORAGE_GAME_VARIABLE_USED] = []
  end
 
  #save current party
  $game_variables[STORAGE_GAME_VARIABLE_USED][storageNumberPrevious]=$PokemonStorage
 
  #if no old storage was set make it a blank one else load the saved one
  if(storageNumberNext.nil? || !$game_variables[STORAGE_GAME_VARIABLE_USED][storageNumberNext])
    $PokemonStorage = PokemonStorage.new
  else
    $PokemonStorage = $game_variables[STORAGE_GAME_VARIABLE_USED][storageNumberNext]
  end
  #storage switched ... return true
  return true
end