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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 process_alias_import_namespace(namespace):
 """ Validate input arguments when the user invokes 'az alias import'. Args: namespace: argparse namespace object. """

    if is_url(namespace.alias_source):
        alias_source = retrieve_file_from_url(namespace.alias_source)

        _validate_alias_file_content(alias_source, url=namespace.alias_source)
    else:
        namespace.alias_source = os.path.abspath(namespace.alias_source)
        _validate_alias_file_path(namespace.alias_source)
        _validate_alias_file_content(namespace.alias_source)