code: def _vertex_data_to_sframe(data, vid_field):
      
      if isinstance(data, SFrame):
          # '__id' already in the sframe, and it is ok to not specify vid_field
          if vid_field is None and _VID_COLUMN in data.column_names():
              return data
          if vid_field is None:
              raise ValueError("vid_field must be specified for SFrame input")
          data_copy = copy.copy(data)
          data_copy.rename({vid_field: _VID_COLUMN}, inplace=True)
          return data_copy
  
      if type(data) == Vertex or type(data) == list:
          return _vertex_list_to_sframe(data, '__id')
  
      elif HAS_PANDAS and type(data) == pd.DataFrame:
          if vid_field is None:
              # using the dataframe index as vertex id
              if data.index.is_unique:
                  if not ("index" in data.columns):
                      # pandas reset_index() will insert a new column of name "index".
                      sf = SFrame(data.reset_index())  # "index"
                      sf.rename({'index': _VID_COLUMN}, inplace=True)
                      return sf
                  else:
                      # pandas reset_index() will insert a new column of name "level_0" if there exists a column named "index".
                      sf = SFrame(data.reset_index())  # "level_0"
                      sf.rename({'level_0': _VID_COLUMN}, inplace=True)
                      return sf
              else:
                  raise ValueError("Index of the vertices dataframe is not unique, \
                          try specifying vid_field name to use a column for vertex ids.")
          else:
              sf = SFrame(data)
              if _VID_COLUMN in sf.column_names():
                  raise ValueError('%s reserved vid column name already exists in the SFrame' % _VID_COLUMN)
              sf.rename({vid_field: _VID_COLUMN}, inplace=True)
              return sf
      else:
          raise TypeError('Vertices type %s is Not supported.' % str(type(data)))
docs: Convert data into a vertex data sframe. Using vid_field to identify the id
      column. The returned sframe will have id column name '__id'.