p 'abcd'.start_with?('ab')  #returns true
p 'abcd'.end_with?('ab')    #returns false
p 'abab'.include?('bb')     #returns false
p 'abab'.include?('ab')     #returns true
p 'abab'['bb']              #returns nil
p 'abab'['ab']              #returns "ab"
p 'abab'.index('bb')        #returns nil
p 'abab'.index('ab')        #returns 0
p 'abab'.index('ab', 1)     #returns 2
p 'abab'.rindex('ab')       #returns 2