code: def _index_to_label(index):
      """Convert a pandas index or multiindex to an axis label."""
      if isinstance(index, pd.MultiIndex):
          return "-".join(map(to_utf8, index.names))
      else:
          return index.name
  
imports: import warnings
  import matplotlib
  from matplotlib.collections import LineCollection
  import matplotlib.pyplot
  from matplotlib import gridspec
  import numpy
  import pandas
  from .None import cm
  from .axisgrid import Grid
  from ._compat import get_colormap
  from .utils import despine, axis_ticklabels_overlap, relative_luminance, to_utf8, _draw_figure
label_desc: Use image node_id 1 for calling a global function with example usage: _index_to_label(index) and returns: str, index