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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def register_type(env_type, alias=None):
 """Registers environment type. :param str|unicode|Environment env_type: Environment type or its alias (for already registered types). :param str|unicode alias: Alias to register type under. If not set type name is used. :rtype: Environment """

    if isinstance(env_type, string_types):
        env_type = TYPES[env_type]

    if alias is None:
        alias = env_type.name

    TYPES[alias] = env_type

    for alias in env_type.aliases:
        TYPES[alias] = env_type

    return env_type