parameters: (self, files=None, cwd='/')
docstring: Initializes a "mock" filesystem that can be used to completely
          stub out a filesystem.
  
          Args:
              files: a dict of filenames -> file contents. A file contents
                  value of None is used to indicate that the file should
                  not exist.
docstring_summary: Initializes a "mock" filesystem that can be used to completely
          stub out a filesystem.
docstring_tokens: Initializes a mock filesystem that can be used to completely stub out a filesystem .
function: def __init__(self, files=None, cwd='/'):
          """Initializes a "mock" filesystem that can be used to completely
          stub out a filesystem.
  
          Args:
              files: a dict of filenames -> file contents. A file contents
                  value of None is used to indicate that the file should
                  not exist.
          """
          self.files = files or {}
          self.written_files = {}
          self._sep = '/'
          self.current_tmpno = 0
          self.cwd = cwd
          self.dirs = {}
function_tokens: def __init__ ( self , files = None , cwd = '/' ) : self . files = files or { } self . written_files = { } self . _sep = '/' self . current_tmpno = 0 self . cwd = cwd self . dirs = { }