old_contents: import os
  import shutil
  
  from wmt.config import site
  from wmt.models.submissions import prepend_to_path
  from wmt.utils.hook import find_simulation_input_file
  from topoflow_utils.hook import assign_parameters
  
  
  file_list = ['rti_file',
               'pixel_file']
  
  
  def execute(env):
      """Perform pre-stage tasks for running a component.
  
      Parameters
      ----------
      env : dict
        A dict of component parameter values from WMT.
  
      """
      env['n_steps'] = int(round(float(env['run_duration']) / float(env['dt'])))
      env['save_grid_dt'] = float(env['dt'])
      env['save_pixels_dt'] = float(env['dt'])
  
      # TopoFlow needs site_prefix and case_prefix.
      env['site_prefix'] = os.path.splitext(env['rti_file'])[0]
      env['case_prefix'] = 'WMT'
  
      # If no pixel_file is given, let TopoFlow make one.
      if env['pixel_file'] == 'off':
          file_list.remove('pixel_file')
          env['pixel_file'] = env['case_prefix'] + '_outlets.txt'
  
      assign_parameters(env, file_list)
  
      # Default files common to all TopoFlow components are stored with the
      # topoflow component metadata.
      prepend_to_path('WMT_INPUT_FILE_PATH',
                      os.path.join(site['db'], 'components', 'topoflow', 'files'))
      for fname in file_list:
          src = find_simulation_input_file(env[fname])
          shutil.copy(src, os.curdir)
  
new_contents: import os
  import shutil
  
  from wmt.config import site
  from wmt.utils.hook import find_simulation_input_file
  from topoflow_utils.hook import assign_parameters, scalar_to_rtg_file
  
  
  file_list = []
  
  
  def execute(env):
      """Perform pre-stage tasks for running a component.
  
      Parameters
      ----------
      env : dict
        A dict of component parameter values from WMT.
  
      """
      env['n_steps'] = int(round(float(env['run_duration']) / float(env['dt'])))
      env['save_grid_dt'] = float(env['dt'])
      env['save_pixels_dt'] = float(env['dt'])
  
      assign_parameters(env, file_list)
  
      for fname in file_list:
          src = find_simulation_input_file(env[fname])
          shutil.copy(src, os.curdir)
      src = find_simulation_input_file(env['site_prefix'] + '.rti')
      shutil.copy(src, os.path.join(os.curdir, env['site_prefix'] + '.rti'))
  
      for var in ('rho_snow', 'c0', 'T0', 'h0_snow', 'h0_swe'):
          if env[var + '_ptype'] == 'Scalar':
              scalar_to_rtg_file(var, env)
  
subject: Update hook for SnowDegreeDay component