From: Ruby Newbee <rubynewbee@...>
Date: 2009-11-24T22:41:41+09:00
Subject: can't understand for String.delete

     Returns a copy of _str_ with all characters in the intersection of
     its arguments deleted. Uses the same rules for building the set of
     characters as +String#count+.

        "hello".delete "l","lo"        #=> "heo"
        "hello".delete "lo"            #=> "he"
        "hello".delete "aeiou", "^e"   #=> "hell"
        "hello".delete "ej-m"          #=> "ho"


What does this mean?
I can't understand for the rules.

Thanks.