class_docstr: A GP class, inherited from Optimizer.
  
  This is the designed class to define GP-related
  variables and methods.
  
  References:
      J. Koza. Genetic programming: On the programming of computers by means of natural selection (1992).
docstr: Probability of crossover.
docstr_tok: ["Probability","of","crossover","."]
code: def p_crossover(self) -> float:
      """Probability of crossover."""
  
      return self._p_crossover
  
imports: import copy
  import time
  from typing import Any, Dict, Optional, Tuple
  import numpy
  import opytimizer.math.general
  import opytimizer.math.random
  import opytimizer.utils.exception
  from opytimizer.core import Optimizer
  from opytimizer.core.function import Function
  from opytimizer.core.node import Node
  from opytimizer.core.space import Space
  from opytimizer.spaces.tree import TreeSpace
  from opytimizer.utils import logging
label_desc: Use image node_id 6 for calling the GP obj's underlying member method code with example usage: obj.p_crossover() and returns: self