class_docstr: Class for encoding the CNF expression.
code: def __init__(self, data=None, encoding=None):
      if not data and not encoding:
          data = []
          encoding = {}
      self.data = data
      self.encoding = encoding
      self._symbols = list(encoding.keys())
  
imports: from itertools import combinations, product, zip_longest
  from sympy.assumptions.assume import AppliedPredicate, Predicate
  from sympy.core.relational import Eq, Ne, Gt, Lt, Ge, Le
  from sympy.core.singleton import S
  from sympy.logic.boolalg import Or, And, Not, Xnor
  from sympy.logic.boolalg import Equivalent, ITE, Implies, Nand, Nor, Xor
label_desc: Use image node_id 1 to create a new EncodedCNF object  with example: obj = EncodedCNF(data, encoding)