@classmethod
def var(cls, var_name, view=None, name=None, dtype=None, **kwargs) ->'url':
    """Implements having url-arguments. dtype is the casting argument.
        the default cast-type is str as Django."""
    route = f'{dtype}:{var_name}' if dtype else str(var_name)
    return cls(f'<{route}>', view, name, **kwargs)
