def _split(text):
    """Split a line of text into two similarly sized pieces.

    >>> _split("Hello, world!")
    ('Hello,', 'world!')

    >>> _split("This is a phrase that can be split.")
    ('This is a phrase', 'that can be split.')

    >>> _split("This_is_a_phrase_that_can_not_be_split.")
    ('This_is_a_phrase_that_can_not_be_split.',)

    """
    result = (text,)

    if len(text) >= 3 and ' ' in text[1:-1]:  # can split this string
        space_indices = [i for i in range(len(text)) if text[i] == ' ']
        space_proximities = [abs(i - len(text) // 2) for i in space_indices]
        for i, j in zip(space_proximities, space_indices):
            if i == min(space_proximities):
                result = (text[:j], text[j + 1:])
                break

    return result