human
Complete the below
def gtkformat_factory(format, colnum):

    ''''copy the format, perform any overrides, and attach an gtk style attrs
    xalign = 0.
    cell = None'
    '''

=====
What is a the Python code you requested?
assistant
#Here is the Python code you requested.
    if (format is None):
        return None
    format = copy.copy(format)
    format.xalign = 0.0
    format.cell = None
    def negative_red_cell(column, cell, model, thisiter):
        val = model.get_value(thisiter, colnum)
        try:
            val = float(val)
        except:
            cell.set_property(u'foreground', u'black')
        else:
            if (val < 0):
                cell.set_property(u'foreground', u'red')
            else:
                cell.set_property(u'foreground', u'black')
    if (isinstance(format, mlab.FormatFloat) or isinstance(format, mlab.FormatInt)):
        format.cell = negative_red_cell
        format.xalign = 1.0
    elif isinstance(format, mlab.FormatDate):
        format.xalign = 1.0
    return format