code: def _hashable(x):
      """ensure that an point is hashable by a python dict"""
      return tuple(map(float, x))
  
imports: import numpy
  from warnings import warn
  from .util import ensure_rng, NotUniqueError
  from .util import Colours
label_desc: Use image node_id 1 for calling a global function with example usage: _hashable(x) and returns: tuple