Initial data commit

Task/Symmetric-difference/Icon/symmetric-difference.icon

@@ -0,0 +1,19 @@
+procedure main()
+
+a := set(["John", "Serena", "Bob", "Mary", "Serena"])
+b := set(["Jim", "Mary", "John", "Jim", "Bob"])
+
+showset("a",a)
+showset("b",b)
+showset("(a\\b) \xef (b\\a)",(a -- b) ++ (b -- a))
+showset("(a\\b)",a -- b)
+showset("(b\\a)",b -- a)
+end
+
+
+procedure showset(n,x)
+writes(n," = { ")
+every writes(!x," ")
+write("}")
+return
+end