code: def _big_delta_coeff(aa, bb, cc, prec=None):
      r"""
      Calculates the Delta coefficient of the 3 angular momenta for
      Racah symbols. Also checks that the differences are of integer
      value.
  
      Parameters
      ==========
  
      aa :
          First angular momentum, integer or half integer.
      bb :
          Second angular momentum, integer or half integer.
      cc :
          Third angular momentum, integer or half integer.
      prec :
          Precision of the ``sqrt()`` calculation.
  
      Returns
      =======
  
      double : Value of the Delta coefficient.
  
      Examples
      ========
  
          sage: from sage.functions.wigner import _big_delta_coeff
          sage: _big_delta_coeff(1,1,1)
          1/2*sqrt(1/6)
      """
  
      if not int_valued(aa + bb - cc):
          raise ValueError(
              "j values must be integer or half integer and fulfill the triangle relation"
          )
      if not int_valued(aa + cc - bb):
          raise ValueError(
              "j values must be integer or half integer and fulfill the triangle relation"
          )
      if not int_valued(bb + cc - aa):
          raise ValueError(
              "j values must be integer or half integer and fulfill the triangle relation"
          )
      if (aa + bb - cc) < 0:
          return S.Zero
      if (aa + cc - bb) < 0:
          return S.Zero
      if (bb + cc - aa) < 0:
          return S.Zero
  
      maxfact = max(
          aa + bb - cc, aa + cc - bb, bb + cc - aa, aa + bb + cc + 1
      )
      _calc_factlist(maxfact)
  
      argsqrt = Integer(
          _Factlist[int(aa + bb - cc)]
          * _Factlist[int(aa + cc - bb)]
          * _Factlist[int(bb + cc - aa)]
      ) / Integer(_Factlist[int(aa + bb + cc + 1)])
  
      ressqrt = sqrt(argsqrt)
      if prec:
          ressqrt = ressqrt.evalf(prec).as_real_imag()[0]
      return ressqrt
  
imports: from sympy.concrete.summations import Sum
  from sympy.core.add import Add
  from sympy.core.numbers import int_valued
  from sympy.core.function import Function
  from sympy.core.numbers import I, Integer, pi
  from sympy.core.singleton import S
  from sympy.core.symbol import Dummy
  from sympy.core.sympify import sympify
  from sympy.functions.combinatorial.factorials import binomial, factorial
  from sympy.functions.elementary.complexes import re
  from sympy.functions.elementary.exponential import exp
  from sympy.functions.elementary.miscellaneous import sqrt
  from sympy.functions.elementary.trigonometric import cos, sin
  from sympy.functions.special.spherical_harmonics import Ynm
  from sympy.matrices.dense import zeros
  from sympy.matrices.immutable import ImmutableMatrix
  from sympy.utilities.misc import as_int
label_desc: Use image node_id 4 for calling a global function with example usage: _big_delta_coeff(aa, bb, cc, prec) and returns: ressqrt, S, S, S