code: def _env_root(repo, saltenv):
      '''
      Return the root of the directory corresponding to the desired environment,
      or None if the environment was not found.
      '''
      # If 'base' is desired, look for the trunk
      if saltenv == 'base':
          trunk = os.path.join(repo['repo'], repo['trunk'])
          if os.path.isdir(trunk):
              return trunk
          else:
              return None
  
      # Check branches
      branches = os.path.join(repo['repo'], repo['branches'])
      if os.path.isdir(branches) and saltenv in os.listdir(branches):
          return os.path.join(branches, saltenv)
  
      # Check tags
      tags = os.path.join(repo['repo'], repo['tags'])
      if os.path.isdir(tags) and saltenv in os.listdir(tags):
          return os.path.join(tags, saltenv)
  
      return Nonf _env_root(repo, saltenv):
      '''
      Return the root of the directory corresponding to the desired environment,
      or None if the environment was not found.
      '''
      # If 'base' is desired, look for the trunk
      if saltenv == 'base':
          trunk = os.path.join(repo['repo'], repo['trunk'])
          if os.path.isdir(trunk):
              return trunk
          else:
              return None
  
      # Check branches
      branches = os.path.join(repo['repo'], repo['branches'])
      if os.path.isdir(branches) and saltenv in os.listdir(branches):
          return os.path.join(branches, saltenv)
  
      # Check tags
      tags = os.path.join(repo['repo'], repo['tags'])
      if os.path.isdir(tags) and saltenv in os.listdir(tags):
          return os.path.join(tags, saltenv)
  
      return None
docs: Return the root of the directory corresponding to the desired environment,
      or None if the environment was not found.