'A |Length| value calculated from the values of `w:ind/@w:firstLine`
and `w:ind/@w:hanging`. Returns |None| if the `w:ind` child is not
present.'

@property
def first_line_indent(self):

    ind = self.ind
    if (ind is None):
        return None
    hanging = ind.hanging
    if (hanging is not None):
        return Length((- hanging))
    firstLine = ind.firstLine
    if (firstLine is None):
        return None
    return firstLine
