code: def x_label(self, x_label=None):
          
  
          if x_label is None:
              return self._x_label
          else:
              if not isinstance(x_label, str):
                  raise TypeError("x_label must be str, not '%s'" % str(x_label))
              self._x_label = x_label
docs: Returns or sets (if a value is provided) the chart's x-axis label.
  
          :param str x_label: If given, the chart's x_label will be set to this.
          :rtype: ``str``