code: def __tt_dot_dot(i, x, p_0, statistic, eps):
      """Second numerical derivative of __tt."""
      e = np.zeros(x.shape)
      e[i] = 1
      return (
          __tt_dot(i, x, p_0, statistic, eps) / eps
          + (
              __tt(x, ((1 - eps) * p_0 - eps * e[i]), statistic)
              - __tt(x, p_0, statistic)
          )
          / eps**2
      )
  
file_path: dipy/dipy/boots/resampling.py
imports: import numpy
  import scipy
  import warnings
label_desc: Use image node_id 8 for calling a global function with example usage: __tt_dot_dot(i, x, p_0, statistic, eps) and returns: unknown