code: def main():
      x = sympy.Symbol("x")
      y = sympy.Symbol("y")
  
      e = 1 / sympy.cos(x)
      print()
      pprint(e)
      print("\n")
      pprint(e.subs(sympy.cos(x), y))
      print("\n")
      pprint(e.subs(sympy.cos(x), y).subs(y, x**2))
  
      e = 1 / sympy.log(x)
      e = e.subs(x, sympy.Float("2.71828"))
      print("\n")
      pprint(e)
      print("\n")
      pprint(e.evalf())
      print()
  
      a = sympy.Symbol("a")
      b = sympy.Symbol("b")
      e = a * 2 + a**b / a
      print("\n")
      pprint(e)
      a = 2
      print("\n")
      pprint(e.subs(a, 8))
      print()
  
label_desc: Use image node_id 1 for calling a global function with example usage: main() without return types