《21_Hashes_and_Symbols》
（提示：如果视频分为多个小段，请下载后用视频合并软件合并。）教程列表：
Ruby_Programming_15_Find_and_Replace_Program
Ruby_Programming_14_All_about_Loops
Ruby_Programming_13_Pythagorean_Theorem_Calculator
Ruby_Programming_12_Functions_with_Numbers
Ruby_Programming_11_counter_index_each_do
Ruby_Programming_5_split_and_arrays
Ruby_Programming_10_Functions
Ruby_Programming_9_More_on_Hashes
Ruby_Programming_8_gets.chomp_Method
Ruby_Programming_7_Write_a_Hash
Ruby_Programming_32_Ruby_Procs_Explained
Ruby_Programming_31_Yield
Ruby_Programming_30_Shovel_Operator
Ruby_Programming_24_CRUD_Part_2_of_2
Ruby_Programming_23_CRUD_Create_Read_Update_Delete
Ruby_Programming_22_Add_an_Item_to_a_Hash
Ruby_Programming_21_Hashes_and_Symbols
Ruby_Programming_20_How_to_Write_a_Sort_Method
Ruby_Programming_19_Combined_Comparison_Operator_(Spaceship_Operator)
Ruby_Programming_36_FizzBuzz_Game
Ruby_Programming_17_Find_Prime_Numbers
Ruby_Programming_16_Multidimensional_Arrays
Ruby_Programming_6_How_to_Write_Arrays_in_Ruby
Ruby_Programming_3_if_else_elsif
Ruby_Programming_2_Arithmetic_Operators_Tutorial
Ruby_Programming_1_Install_Ruby_and_Editor
Ruby_Programming_1.1_Komodo_IDE
Ruby_Programming_18_Histogram_and_Sorting
Ruby_Programming_35_Ruby_Global_Variables
Ruby_Programming_34_Ruby_Classes
Ruby_Programming_4_Formatting_capitalize_upcase_downcase_reverse_length
Ruby_Programming_33_Ruby_Lambdas_Explained