code: def test_gosper_nan():
      a = Symbol("a", positive=True)
      b = Symbol("b", positive=True)
      n = Symbol("n", integer=True)
      m = Symbol("m", integer=True)
      f2d = (
          n
          * (n + a + b)
          * a**n
          * b**n
          / (factorial(n + a) * factorial(n + b))
      )
      g2d = 1 / (factorial(a - 1) * factorial(b - 1)) - a ** (
          m + 1
      ) * b ** (m + 1) / (factorial(a + m) * factorial(b + m))
      g = gosper_sum(f2d, (n, 0, m))
      assert simplify(g - g2d) == 0
  
imports: from sympy.core.numbers import Rational, pi
  from sympy.core.singleton import S
  from sympy.core.symbol import Symbol
  from sympy.functions.combinatorial.factorials import binomial, factorial
  from sympy.functions.elementary.exponential import exp, log
  from sympy.functions.elementary.miscellaneous import sqrt
  from sympy.functions.special.gamma_functions import gamma
  from sympy.polys.polytools import Poly
  from sympy.simplify.simplify import simplify
  from sympy.concrete.gosper import gosper_normal, gosper_sum, gosper_term
  from sympy.abc import a, b, j, k, m, n, r, x
label_desc: Use image node_id 10 for calling a global function with example usage: test_gosper_nan() without return types