code: def test_function_series1():
      """Create our new "sin" function."""
  
      class my_function(Function):
          def fdiff(self, argindex=1):
              return cos(self.args[0])
  
          @classmethod
          def eval(cls, arg):
              arg = sympify(arg)
              if arg == 0:
                  return sympify(0)
  
      # Test that the taylor series is correct
      assert my_function(x).series(x, 0, 10) == sin(x).series(x, 0, 10)
      assert limit(my_function(x) / x, x, 0) == 1
  
file_path: sympy/sympy/functions/elementary/tests/test_interface.py
imports: from sympy.core.function import Function
  from sympy.core.sympify import sympify
  from sympy.functions.elementary.hyperbolic import tanh
  from sympy.functions.elementary.trigonometric import cos, sin
  from sympy.series.limits import limit
  from sympy.abc import x
label_desc: Use image node_id 1 for calling a global function with example usage: test_function_series1() and returns: cos, sympify