code: def _test(n, base, s, t):
      """Miller-Rabin strong pseudoprime test for one base.
      Return False if n is definitely composite, True if n is
      probably prime, with a probability greater than 3/4.
  
      """
      # do the Fermat test
      b = pow(base, t, n)
      if b == 1 or b == n - 1:
          return True
      for _ in range(s - 1):
          b = pow(b, 2, n)
          if b == n - 1:
              return True
          # see I. Niven et al. "An Introduction to Theory of Numbers", page 78
          if b == 1:
              return False
      return False
  
imports: from itertools import count
  from sympy.core.sympify import sympify
  from sympy.external.gmpy import gmpy, gcd, jacobi, is_square, bit_scan1, is_fermat_prp, is_euler_prp, is_selfridge_prp, is_strong_selfridge_prp, is_strong_bpsw_prp
  from sympy.external.ntheory import _lucas_sequence
  from sympy.utilities.misc import as_int, filldedent
label_desc: Use image node_id 5 for calling a global function with example usage: _test(n, base, s, t) and returns: False, True, True, False