old_contents: #!/usr/bin/env python
  """
  Compiler tool.
  """
  
  from optparse import OptionParser
  import sys
  import os
  import fnmatch
  import logging
  
  logger = logging.getLogger("pymola")
  
  # Parse command line arguments
  usage = "usage: %prog [options] MODEL_FOLDER MODEL_NAME"
  parser = OptionParser(usage)
  parser.add_option("-c", "--casadi", dest="casadi_folder",
                    help="CasADi installation folder")
  parser.add_option("-f", "--flatten_only",
                    action="store_true", dest="flatten_only")
  parser.add_option("-v", "--verbose",
                    action="store_true", dest="verbose")
  (options, args) = parser.parse_args()
  if len(args) != 2:
      parser.error("incorrect number of arguments")
  
  model_folder = args[0]
  model_name = args[1]
  
  # Set log level
  logging.basicConfig(level=logging.DEBUG if options.verbose else logging.INFO)
  
  # Import rest of pymola
  from pymola import parser, tree    
  
  # Compile
  if options.flatten_only:
      # Load folder
      ast = None
      for root, dir, files in os.walk(model_folder, followlinks=True):
          for item in fnmatch.filter(files, "*.mo"):
              logger.info("Parsing {}".format(item))
  
              with open(os.path.join(root, item), 'r') as f:
                  if ast is None:
                      ast = parser.parse(f.read())
                  else:
                      ast.extend(parser.parse(f.read()))
  
      logger.info("Flattening")
  
      ast = tree.flatten(ast, model_name)
      print(ast)
  else:
      # Set CasADi installation folder
      if options.casadi_folder is not None:
          sys.path.append(options.casadi_folder)
  
      from pymola.backends.casadi.api import transfer_model
      import casadi as ca
  
      logger.info("Generating CasADi model")
      
      compiler_options = \
          {'replace_constants': True,
           'replace_parameter_expressions': True,
           'eliminable_variable_expression': r'_\w+',
           'detect_aliases': True,
           'expand': False,
           'cache': True}
  
      model = transfer_model(model_folder, model_name, compiler_options)
      print(model)
  
new_contents: #!/usr/bin/env python
  """
  Compiler tool.
  """
  
  from optparse import OptionParser
  import sys
  import os
  import fnmatch
  import logging
  
  logger = logging.getLogger("pymola")
  
  # Parse command line arguments
  usage = "usage: %prog [options] MODEL_FOLDER MODEL_NAME"
  parser = OptionParser(usage)
  parser.add_option("-c", "--casadi", dest="casadi_folder",
                    help="CasADi installation folder")
  parser.add_option("-f", "--flatten_only",
                    action="store_true", dest="flatten_only")
  parser.add_option("-v", "--verbose",
                    action="store_true", dest="verbose")
  (options, args) = parser.parse_args()
  if len(args) != 2:
      parser.error("incorrect number of arguments")
  
  model_folder = args[0]
  model_name = args[1]
  
  # Set log level
  logging.basicConfig(level=logging.DEBUG if options.verbose else logging.INFO)
  
  # Import rest of pymola
  from pymola import parser, tree, ast
  
  # Compile
  if options.flatten_only:
      # Load folder
      _ast = None
      for root, dir, files in os.walk(model_folder, followlinks=True):
          for item in fnmatch.filter(files, "*.mo"):
              logger.info("Parsing {}".format(item))
  
              with open(os.path.join(root, item), 'r') as f:
                  if _ast is None:
                      _ast = parser.parse(f.read())
                  else:
                      _ast.extend(parser.parse(f.read()))
  
      logger.info("Flattening")
  
      _ast = tree.flatten(_ast, ast.ComponentRef(name=model_name))
      print(_ast)
  else:
      # Set CasADi installation folder
      if options.casadi_folder is not None:
          sys.path.append(options.casadi_folder)
  
      from pymola.backends.casadi.api import transfer_model
      import casadi as ca
  
      logger.info("Generating CasADi model")
      
      compiler_options = \
          {'replace_constants': True,
           'replace_parameter_expressions': True,
           'eliminable_variable_expression': r'_\w+',
           'detect_aliases': True,
           'expand': False,
           'cache': True}
  
      model = transfer_model(model_folder, model_name, compiler_options)
      print(model)
  
subject: Fix flattening mode in compiler.py.