@staticmethod
    def _param_to_str(param):
        """Represent a parameter as a string.

        :rtype: str
        """
        result = '{open_char}{arg_name}{type_name}{default}{close_char}'
        if (param.kind == param.VAR_POSITIONAL or
                param.default is not param.empty):
            open_char = '['
            close_char = ']'
        else:
            open_char = '<'
            close_char = '>'

        if param.default is not param.empty:
            default = '=' + str(param.default)
        else:
            default = ''

        if param.annotation is not param.empty:
            type_name = ':' + param.annotation.__name__
        else:
            type_name = ''

        if param.kind == param.VAR_POSITIONAL:
            arg_name = '*' + param.name
        else:
            arg_name = param.name

        return result.format(open_char=open_char, arg_name=arg_name,
            type_name=type_name, default=default, close_char=close_char)