code: def find(x, equation):
      """
      Checks whether a Symbol matching ``x`` is present in ``equation``
      or not. If present, the matching symbol is returned, else a
      ValueError is raised. If ``x`` is a string the matching symbol
      will have the same name; if ``x`` is a Symbol then it will be
      returned if found.
  
      Examples
      ========
  
      >>> from sympy.geometry.util import find
      >>> from sympy import Dummy
      >>> from sympy.abc import x
      >>> find('x', x)
      x
      >>> find('x', Dummy('x'))
      _x
  
      The dummy symbol is returned since it has a matching name:
  
      >>> _.name == 'x'
      True
      >>> find(x, Dummy('x'))
      Traceback (most recent call last):
      ...
      ValueError: could not find x
      """
  
      free = equation.free_symbols
      xs = [
          i for i in free if (i.name if isinstance(x, str) else i) == x
      ]
      if not xs:
          raise ValueError("could not find %s" % x)
      if len(xs) != 1:
          raise ValueError("ambiguous %s" % x)
      return xs[0]
  
imports: from collections import deque
  from math import sqrt
  from sympy import nsimplify
  from .entity import GeometryEntity
  from .exceptions import GeometryError
  from .point import Point, Point2D, Point3D
  from sympy.core.containers import OrderedSet
  from sympy.core.exprtools import factor_terms
  from sympy.core.function import Function, expand_mul
  from sympy.core.numbers import Float
  from sympy.core.sorting import ordered
  from sympy.core.symbol import Symbol
  from sympy.core.singleton import S
  from sympy.polys.polytools import cancel
  from sympy.functions.elementary.miscellaneous import sqrt
  from sympy.utilities.iterables import is_sequence
  from mpmath.libmp.libmpf import prec_to_dps
label_desc: Use image node_id 1 for calling a global function with example usage: find(x, equation) and returns: xs