def constantize(str)
      str = str.to_s
      call_or_yield str do
        raise(NameError, "#{s.inspect} is not a valid constant name!") unless m = VALID_CONSTANT_NAME_REGEXP.match(str)
        Object.module_eval("::#{m[1]}", __FILE__, __LINE__)
      end
    end
def constantize(str)
      str = str.to_s
      call_or_yield str do
        raise(NameError, "#{s.inspect} is not a valid constant name!") unless m = VALID_CONSTANT_NAME_REGEXP.match(str)
        Object.module_eval("::#{m[1]}", __FILE__, __LINE__)
      end
    end
Tries to find a constant with the name specified in the argument string.
 @param [String] str
 @return [Object]