text: samp_string = 'Whatever you are, be a good one.'
  
  # You can get a character by referencing an index
  print(samp_string[0])
  
  # get the last character
  print(samp_string[-1])
  
  # get the string length
  print('Length : ', len(samp_string))
  
  # Get a slice by saying where to start and end
  # The 4th index isn't returned
  print(samp_string[0:4])
  
  # Get everything starting at an index
  print(samp_string[8:])
  print()
  
  print(samp_string)
  print(samp_string[::])
  print(samp_string[::2])
  
  # Reverse the string
  print(samp_string[::-1])
  # Palindrome
  print('I did, did I?'[::-1])
  print('No lenmon, no melon'[::-1])
  
  # Practical use
  url = "http://pythonabc.org"
  # Get the top level domain
  print(url[-4:])
  # Print the url without the http://
  print(url[7:])
  # Print the url without the http:// or the top level domain
  print(url[7:-4])
  
  # Cycle through each character with for
  for char in samp_string:
      print(char)
  
  # Cycle through charcters in pairs
  # 这一段程序只对长度为偶数的有效，要程序更有包容性，可用的方法之一是分类讨论。
  for i in range(0, len(samp_string)-1, 2):
      print(samp_string[i] + samp_string[i+1])
  
  # Join or concatenate strings with +
  print('Green' + 'egg')
  
  # Repeat string with *
  print("Hello" * 5)
  
  # Convert an int into a string
  num_string = str(4)
  
  # Computers assign characters with a number known as a Unicode
  # A - Z 65 - 90
  # a - z 97 - 122
  
  # You can get the Unicode with ord()
  print("A =", ord("A"))
  
  # You can convert from Unicode with chr()
  print("65 = ", chr(65))
  
  print("桃 = ", ord("桃"))
  print("26691 = ", chr(26691))