code: def MCC_calc(TP, TN, FP, FN):
      """
      Calculate Matthews correlation coefficient (MCC).
  
      :param TP: true positive
      :type TP: int
      :param TN: true negative
      :type TN: int
      :param FP: false positive
      :type FP: int
      :param FN: false negative
      :type FN: int
      :return: MCC as float
      """
      try:
          result = (TP * TN - FP * FN) / (
              math.sqrt((TP + FP) * (TP + FN) * (TN + FP) * (TN + FN))
          )
          return result
      except (ZeroDivisionError, TypeError, ValueError):
          return "None"
  
imports: from __future__ import division
  import math
  from .pycm_util import normal_quantile
  from .pycm_interpret import *
  from .pycm_param import CLASS_PARAMS
label_desc: Use image node_id 14 for calling a global function with example usage: MCC_calc(TP, TN, FP, FN) and returns: result, str