Returns true if 'v' is either implicit value, or
    the part before the first '-' symbol is implicit value.

def looks_like_implicit_value(v):
    """Returns true if 'v' is either implicit value, or
    the part before the first '-' symbol is implicit value."""
    assert isinstance(v, basestring)
    if feature.is_implicit_value(v):
        return 1
    else:
        split = v.split("-")
        if feature.is_implicit_value(split[0]):
            return 1

    return 0