code: def _symbol(s, matching_symbol=None, **assumptions):
      """Return s if s is a Symbol, else if s is a string, return either
      the matching_symbol if the names are the same or else a new symbol
      with the same assumptions as the matching symbol (or the
      assumptions as provided).
  
      Examples
      ========
  
      >>> from sympy import Symbol
      >>> from sympy.core.symbol import _symbol
      >>> _symbol('y')
      y
      >>> _.is_real is None
      True
      >>> _symbol('y', real=True).is_real
      True
  
      >>> x = Symbol('x')
      >>> _symbol(x, real=True)
      x
      >>> _.is_real is None  # ignore attribute if s is a Symbol
      True
  
      Below, the variable sym has the name 'foo':
  
      >>> sym = Symbol('foo', real=True)
  
      Since 'x' is not the same as sym's name, a new symbol is created:
  
      >>> _symbol('x', sym).name
      'x'
  
      It will acquire any assumptions give:
  
      >>> _symbol('x', sym, real=False).is_real
      False
  
      Since 'foo' is the same as sym's name, sym is returned
  
      >>> _symbol('foo', sym)
      foo
  
      Any assumptions given are ignored:
  
      >>> _symbol('foo', sym, real=False).is_real
      True
  
      NB: the symbol here may not be the same as a symbol with the same
      name defined elsewhere as a result of different assumptions.
  
      See Also
      ========
  
      sympy.core.symbol.Symbol
  
      """
      if isinstance(s, str):
          if matching_symbol and matching_symbol.name == s:
              return matching_symbol
          return Symbol(s, **assumptions)
      elif isinstance(s, Symbol):
          return s
      else:
          raise ValueError(
              "symbol must be string for symbol name or Symbol"
          )
  
imports: from __future__ import annotations
  from .assumptions import StdFactKB, _assume_defined
  from .basic import Basic, Atom
  from .cache import cacheit
  from .containers import Tuple
  from .expr import Expr, AtomicExpr
  from .function import AppliedUndef, FunctionClass
  from .kind import NumberKind, UndefinedKind
  from .logic import fuzzy_bool
  from .singleton import S
  from .sorting import ordered
  from .sympify import sympify
  from sympy.logic.boolalg import Boolean
  from sympy.utilities.iterables import sift, is_sequence
  from sympy.utilities.misc import filldedent
  import string
  import re
  import random
  from itertools import product
  from typing import Any
label_desc: Use image node_id 2 for calling a global function with example usage: _symbol(s, matching_symbol) and returns: Symbol, matching_symbol, s