code: def makeAngLenHist(ad, ld, fm = None, collapse=True, fit=spline_base.fit2d):
      
      
      if fm:
          ad,ld = anglendiff(fm, roll=2)
          ad, ld = ad[0], ld[0]
          
      ld = ld[~np.isnan(ld)]
      ad = reshift(ad[~np.isnan(ad)])
  
      if collapse:
          e_y = np.linspace(-36.5, 36.5, 74)
          e_x = np.linspace(0, 180, 181)
          H = makeHist(abs(ad), ld, fit=fit, bins=[e_y, e_x])
  
          H = H/H.sum()
          
          return H
      else:
          e_x = np.linspace(-180, 180, 361)
          e_y = np.linspace(-36.5, 36.5, 74)
          return makeHist(ad, ld, fit=fit, bins=[e_y, e_x])
docs: Histograms and performs a spline fit on the given data, 
      usually angle and length differences.
      
      Parameters:
          ad : array
              The data to be histogrammed along the x-axis. 
              May range from -180 to 180.
          ld : array
              The data to be histogrammed along the y-axis.
              May range from -36 to 36.
          collapse : boolean
              If true, the histogrammed data will include 
              negative values on the x-axis. Else, the histogram
              will be collapsed along x = 0, and thus contain only 
              positive angle differences
          fit : function or None, optional
              The function to use in order to fit the data. 
              If no fit should be applied, set to None
          fm  : fixmat or None, optional
              If given, the angle and length differences are calculated
              from the fixmat and the previous parameters are overwritten.