old_contents: 
  def get_method():
      """"""
      pass
  
new_contents: 
  from . import simple_advection
  from . import steps
  
  def get_method(name):
      """Return one callable function to produce deterministic or ensemble 
      precipitation nowcasts.\n\
      
      Methods for precipitation nowcasting:
      +-------------------+-------------------------------------------------------+
      |     Name          |              Description                              |
      +===================+=======================================================+
      |  extrapolation    |  this method is a simple advection forecast based     |
      |                   |  on Lagrangian persistence                            |
      +-------------------+-------------------------------------------------------+
      |                   | implementation of the STEPS stochastic nowcasting     |
      |  steps            | method as described in Seed (2003), Bowler et al      |
      |                   | (2006) and Seed et al (2013)                          |
      +-------------------+-------------------------------------------------------+
  
      """
      if name.lower() == "extrapolation":
          return simple_advection.forecast
      elif name.lower() == "steps":
          return steps.forecast
      else:
          raise ValueError("unknown nowcasting method %s" % name)
  
subject: Add interface