code: def normalize(self):
          
          median_diff = np.median(np.diff(self.x))
          bin_edges = [self.x[0] - median_diff/2.0]
          bin_edges.extend(median_diff/2.0 + self.x)
          self.y_raw = self.y_raw/(self.y_raw.sum()*np.diff(bin_edges))
          self.smooth()
docs: Normalizes the given data such that the area under the histogram/curve
          comes to 1. Also re applies smoothing once done.