code: def sphere(x, xo=None, yo=None):
      "sphere shifted to have minimum cost at yo and solved x at xo"
      xo = x if xo is None else (np.asarray(x) - xo)
      return mm.sphere(xo) + (0 if yo is None else yo)
  
imports: import mystic.models
  import numpy
label_desc: Use image node_id 2 for calling a global function with example usage: sphere(x, xo, yo) and returns: unknown