@staticmethod
def has(obj, key):
    """
		Returns `True` if the `key` is a key or a defined attribute in `obj`. Otherwise, returns `False`.
		
		Parameters
		----------
		obj : dict or object
			The target to check existence of a key-value pair or an attribute.
		key : str
			A `dict` key or an attribute name.

		Returns
		-------
		bool
			Existence of a key-value pair or an attribute.
		"""
    if isinstance(obj, dict):
        return key in obj
    else:
        return hasattr(obj, key)
