in lib/twitter_cldr/parsers/unicode_regex/character_class.rb [88:107]
def stringify(node)
case node
when UnaryOperator, BinaryOperator
op_str = case node.operator
when :negate then '^'
when :union, :pipe then ''
when :dash then '-'
when :ampersand then '&'
end
left = stringify(node.left)
right = stringify(node.right)
"#{left}#{op_str}#{right}"
else
node.to_s
end
end