class_docstr: Asserts that x is an element of the set S.
  
  Examples
  ========
  
  >>> from sympy import Symbol, Integer, S, Contains
  >>> Contains(Integer(2), S.Integers)
  True
  >>> Contains(Integer(-2), S.Naturals)
  False
  >>> i = Symbol('i', integer=True)
  >>> Contains(i, S.Naturals)
  Contains(i, Naturals)
  
  References
  ==========
  
  .. [1] https://en.wikipedia.org/wiki/Element_%28mathematics%29
code: def binary_symbols(self):
      return set().union(
          *[
              i.binary_symbols
              for i in self.args[1].args
              if i.is_Boolean or i.is_Symbol or isinstance(i, (Eq, Ne))
          ]
      )
  
file_path: sympy/sympy/sets/contains.py
imports: from sympy.core import S
  from sympy.core.sympify import sympify
  from sympy.core.relational import Eq, Ne
  from sympy.core.parameters import global_parameters
  from sympy.logic.boolalg import Boolean
  from sympy.utilities.misc import func_name
  from .sets import Set
label_desc: Use image node_id 2 for calling the Contains obj's underlying member method code with example usage: obj.binary_symbols() and returns: set