code: def Append(self, other):
          
          orig_len = len(self)
          self.Set(orig_len + len(other))
          ipoint = orig_len
          if hasattr(self, 'SetPointError'):
              for point in other:
                  self.SetPoint(ipoint, point.x.value, point.y.value)
                  self.SetPointError(
                      ipoint,
                      point.x.error_low, point.x.error_hi,
                      point.y.error_low, point.y.error_hi)
                  ipoint += 1
          else:
              for point in other:
                  self.SetPoint(ipoint, point.x.value, point.y.value)
                  ipoint += 1
docs: Append points from another graph