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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def evaluate(conditions, leaf_evaluator):
 """ Top level method to evaluate conditions. Args: conditions: Nested array of and/or conditions, or a single leaf condition value of any type. Example: ['and', '0', ['or', '1', '2']] leaf_evaluator: Function which will be called to evaluate leaf condition values. Returns: Boolean: Result of evaluating the conditions using the operator rules and the leaf evaluator. None: if conditions couldn't be evaluated. """


  if isinstance(conditions, list):
    if conditions[0] in list(EVALUATORS_BY_OPERATOR_TYPE.keys()):
      return EVALUATORS_BY_OPERATOR_TYPE[conditions[0]](conditions[1:], leaf_evaluator)
    else:
      # assume OR when operator is not explicit.
      return EVALUATORS_BY_OPERATOR_TYPE[ConditionOperatorTypes.OR](conditions, leaf_evaluator)

  leaf_condition = conditions
  return leaf_evaluator(leaf_condition)