code: def mean(data, units=False, time=False):
      
  
      assert(units is not False or time is not False)
      if units is True and time is False:
          return np.mean(data, axis=0)
      elif units is False and time is True:
          return np.mean(data, axis=1)
      elif units is True and time is True:
          return np.mean(data)
docs: Function to compute mean of data
  
  
      Parameters
      ---------- 
      data : numpy.ndarray
          1st axis unit, 2nd axis time
      units : bool
          Average over units
      time : bool 
          Average over time
  
  
      Returns
      -------
      if units=False and time=False: 
          error
      if units=True: 
          1 dim numpy.ndarray; time series
      if time=True: 
          1 dim numpy.ndarray; series of unit means across time
      if units=True and time=True: 
          float; unit and time mean
  
  
      Examples
      --------
      >>> mean(np.array([[1, 2, 3], [4, 5, 6]]), units=True)
      array([ 2.5,  3.5,  4.5])
  
      >>> mean(np.array([[1, 2, 3], [4, 5, 6]]), time=True)
      array([ 2.,  5.])
  
      >>> mean(np.array([[1, 2, 3], [4, 5, 6]]), units=True,time=True)
      3.5