# ==, !=
- true  : '"a" == "a"'
- false : '"a" != "a"'
- false : '"a" == "b"'
- true  : '"a" != "b"'
- true  : '"" == ""'
- true  : '"" != "a"'
- true  : '("a" | "b" | "c") == ("a" | "b" | "c")'
- true  : '("a" | "b" | "c") != ("c" | "b" | "a")'
- false : '("" | "") == ""'

# +
- true  : '("a" + "b") == "ab"'
- true  : '("a" + "b" + "c") == "abc"'
- false : '("a" + "b" + "c") == ("a" | "b" | "c")'
- true  : '(("a" | "b" | "c") + "a") == ("aa" | "ba" | "ca")'
- true  : '("a" + ("a" | "b" | "c")) == ("aa" | "ab" | "ac")'
- true  : '(("a" | "b" | "c") + ("a" | "b" | "c")) == ("aa" | "ab" | "ac" | "ba" | "bb" | "bc" | "ca" | "cb" | "cc")'

# include?
- true  : '"abc".include?("")'
- true  : '"abc".include?("a")'
- true  : '"abc".include?("ab")'
- true  : '"abc".include?("bc")'
- true  : '"abc".include?("abc")'
- false : '"abc".include?("abcd")'
- 'true | true | true' : '("a" | "b" | "c").include?("")'
- 'true | false | false' : '("a" | "b" | "c").include?("a")'
- 'false | false | false' : '("a" | "b" | "c").include?("ab")'
- 'false | false | false' : '("a" | "b" | "c").include?("abc")'
- 'false | false | false' : '("a" | "b" | "c").include?("abcd")'
- 'false | false | false' : '"".include?("a" | "b" | "c")'
- 'true | false | false' : '"a".include?("a" | "b" | "c")'
- 'true | true | false' : '"ab".include?("a" | "b" | "c")'
- 'true | true | true' : '"abc".include?("a" | "b" | "c")'
- 'true | true | true'  : '"abc".include?("c" | "b" | "a")'
- 'true | false | false | false | true | false | false | false | true'  : '("a" | "b" | "c").include?("a" | "b" | "c")'

# insert
- '"Xabc"' : '"abc".insert(1, "X")'
- '"aXbc"' : '"abc".insert(2, "X")'
- '"abXc"' : '"abc".insert(3, "X")'
- '"abcX"' : '"abc".insert(4, "X")'
- '"Xabc" | "aXbc" | "abXc" | "abcX"' : '"abc".insert(1 | 2 | 3 | 4, "X")'

# count
- true: '"".count == 0'
- true: '"a".count == 1'
- true: '"ab".count == 2'
- true: '"abc".count == 3'
- true: '" ".count == 1'

# substring
- '""' : '"abc".substring(1,0)'
- '"a"' : '"abc".substring(1,1)'
- '"ab"' : '"abc".substring(1,2)'
- '"abc"' : '"abc".substring(1,3)'
- '"abc"' : '"abc".substring(1,4)'
- '"a" | "b" | "c"' : '"abc".substring(1 | 2 | 3, 1)'
- '"a" | "ab" | "abc"' : '"abc".substring(1, 1 | 2 | 3)'
- '"a" | "ab" | "abc" | "b" | "bc" | "bc" | "c" | "c" | "c"' : '"abc".substring(1 | 2 | 3, 1 | 2 | 3)'

# []
- true: '"abc"[0] == "abc"'
- true: '("a" | "b" | "c")[0] == "abc"'

# as_integer, i
- "1" : '"1".as_integer'
- "1" : '"1".i'
- "10" : '"10".i'
- "100" : '"100".i'
- "1" : '"01".i'
- "10" : '"010".i'
- "100" : '"0100".i'
- "-1" : '"-1".i'
- "(1 | 2 | 3)" : '("1" | "2" | "3").i'

# as_float, f
- "1.0" : '"1.0".as_float'
- "1.0" : '"1.0".f'
- "0.1" : '"0.1".f'
- "0.1e10" : '"0.1e10".f'
- "(0.1 | 1.0 | 0.1e10)" : '("0.1" | "1.0" | "0.1e10").f'