'Set the label for the xaxis.
Parameters
xlabel : string
x label
labelpad : scalar, optional, default: None
spacing in points between the label and the x-axis
Other Parameters
**kwargs : `~matplotlib.text.Text` properties
See also
text : for information on how override and the optional args work'

def set_xlabel(self, xlabel, fontdict=None, labelpad=None, **kwargs):

    if (labelpad is not None):
        self.xaxis.labelpad = labelpad
    return self.xaxis.set_label_text(xlabel, fontdict, **kwargs)
