def _is_projective(parse):
    """
    Is the parse tree projective?
    Returns
    --------
    projective : bool
       True if a projective tree.
    """
    for m, h in enumerate(parse):
        for m2, h2 in enumerate(parse):
            if m2 == m:
                continue
            if m < h:
                if (
                    m < m2 < h < h2
                    or m < h2 < h < m2
                    or m2 < m < h2 < h
                    or h2 < m < m2 < h
                ):
                    return False
            if h < m:
                if (
                    h < m2 < m < h2
                    or h < h2 < m < m2
                    or m2 < h < h2 < m
                    or h2 < h < m2 < m
                ):
                    return False
    return True