def get_indefinite_article(noun: str) -> str:
    """
    >>> get_indefinite_article('Elephant')
    'an'
    >>> get_indefinite_article('lion')
    'a'
    >>> get_indefinite_article('  ant')
    'an'
    """
    normalised_noun = noun.lower().strip()

    if not normalised_noun:
        return 'a'

    if normalised_noun[0] in 'aeiou':
        return 'an'
    else:
        return 'a'