class_docstr: Represents Stieltjes constants, $\gamma_{k}$ that occur in
  Laurent Series expansion of the Riemann zeta function.
  
  Examples
  ========
  
  >>> from sympy import stieltjes
  >>> from sympy.abc import n, m
  >>> stieltjes(n)
  stieltjes(n)
  
  The zero'th stieltjes constant:
  
  >>> stieltjes(0)
  EulerGamma
  >>> stieltjes(0, 1)
  EulerGamma
  
  For generalized stieltjes constants:
  
  >>> stieltjes(n, m)
  stieltjes(n, m)
  
  Constants are only defined for integers >= 0:
  
  >>> stieltjes(-1)
  zoo
  
  References
  ==========
  
  .. [1] https://en.wikipedia.org/wiki/Stieltjes_constants
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code: def eval(cls, n, a=None):
      if a is not None:
          a = sympify(a)
          if a is S.NaN:
              return S.NaN
          if a.is_Integer and a.is_nonpositive:
              return S.ComplexInfinity
  
      if n.is_Number:
          if n is S.NaN:
              return S.NaN
          elif n < 0:
              return S.ComplexInfinity
          elif not n.is_Integer:
              return S.ComplexInfinity
          elif n is S.Zero and a in [None, 1]:
              return S.EulerGamma
  
      if n.is_extended_negative:
          return S.ComplexInfinity
  
      if n.is_zero and a in [None, 1]:
          return S.EulerGamma
  
      if n.is_integer == False:
          return S.ComplexInfinity
  
imports: from sympy.core.add import Add
  from sympy.core.cache import cacheit
  from sympy.core.function import ArgumentIndexError, expand_mul, Function
  from sympy.core.numbers import pi, I, Integer
  from sympy.core.relational import Eq
  from sympy.core.singleton import S
  from sympy.core.symbol import Dummy
  from sympy.core.sympify import sympify
  from sympy.functions.combinatorial.numbers import bernoulli, factorial, genocchi, harmonic
  from sympy.functions.elementary.complexes import re, unpolarify, Abs, polar_lift
  from sympy.functions.elementary.exponential import log, exp_polar, exp
  from sympy.functions.elementary.integers import ceiling, floor
  from sympy.functions.elementary.miscellaneous import sqrt
  from sympy.functions.elementary.piecewise import Piecewise
  from sympy.polys.polytools import Poly
label_desc: Use image node_id 1 for calling the stieltjes obj's underlying member method code with example usage: obj.eval(cls, n, a) and returns: S, S, S, S, S, S, S, S, S