def match? label, x
      x.is_a?(Regexp) ? label.to_s =~ x : label == x
    end
def match? label, x
      x.is_a?(Regexp) ? label.to_s =~ x : label == x
    end
compare given label to given expression.
 if expression is a `Regexp` comparing using `=~`.
 otherwise `==` are used

 @param label
 @param x
 @return `true` or `false`