code: def get_data_home(data_home=None):
      
      if data_home is not None:
          return _expand_and_makedir(data_home)
  
      msmb_data = has_msmb_data()
      if msmb_data is not None:
          return _expand_and_makedir(msmb_data)
  
      data_home = environ.get('MSMBUILDER_DATA', join('~', 'msmbuilder_data'))
      return _expand_and_makedir(data_home)
docs: Return the path of the msmbuilder data dir.
  
      As of msmbuilder v3.6, this function will prefer data downloaded via
      the msmb_data conda package (and located within the python installation
      directory). If this package exists, we will use its data directory as
      the data home. Otherwise, we use the old logic:
  
      This folder is used by some large dataset loaders to avoid
      downloading the data several times.
  
      By default the data dir is set to a folder named 'msmbuilder_data'
      in the user's home folder.
  
      Alternatively, it can be set by the 'MSMBUILDER_DATA' environment
      variable or programmatically by giving an explicit folder path. The
      '~' symbol is expanded to the user home folder.
  
      If the folder does not already exist, it is automatically created.