docs: def arr_normalize(arr, *args, **kwargs):
      """
      ARGS
          arr                      array to normalize
  
      **kargs
          scale = <f_scale>        scale the normalized output by <f_scale>
  
  
      DESC
          Given an input array, <arr>, normalize all values to range
          between 0 and 1.
  
          If specified in the **kwargs, optionally set the scale with <f_scale>.
      """
      f_max = arr.max()
      f_min = arr.min()
      f_range = f_max - f_min
      arr_shifted = arr + -f_min
      arr_norm = arr_shifted / f_range
      for key, value in kwargs.items():
          if key == 'scale': arr_norm *= value
      return arr_norm