Add patterns to expand. @example expander = Mustermann::Expander.new expander.add("/:a.jpg", "/:b.png") expander.expand(a: "pony") # => "/pony.jpg" @param [Array<#to_str, Mustermann::Pattern>] patterns list of to add for expansion, Strings will be compiled to patterns. @return [Mustermann::Expander] the expander