code: def _dn(n, prec):
      # controller for n dependence on precision
      # n = starting digit index
      # prec = the number of total digits to compute
      n += 1  # because we subtract 1 for _series
  
      # assert int(math.log(n + prec)/math.log(16)) ==\
      #  ((n + prec).bit_length() - 1) // 4
      return ((n + prec).bit_length() - 1) // 4 + prec + 3
  
imports: from sympy.utilities.misc import as_int
label_desc: Use image node_id 3 for calling a global function with example usage: _dn(n, prec) and returns: unknown