code: def exp4(x, c, a, b, alpha):
      """exp4
  
      Parameters
      ----------
      x : int
      c : float
      a : float
      b : float
      alpha : float
  
      Returns
      -------
      float
          c - np.exp(-a*(x**alpha)+b)
      """
      return c - np.exp(-a * (x**alpha) + b)
  
file_path: nni/nni/algorithms/hpo/curvefitting_assessor/curvefunctions.py
imports: import numpy
label_desc: Use image node_id 9 for calling a global function with example usage: exp4(x, c, a, b, alpha) and returns: unknown