code: def logistic_func(t, amp, off, tau, gamma):
      return (amp - off) / (1 + np.exp(-gamma * (t - tau))) + off
  
imports: import matplotlib.pyplot
  import numpy
  from lmfit import Model
label_desc: Use image node_id 1 for calling a global function with example usage: logistic_func(t, amp, off, tau, gamma) and returns: unknown