input: Write a python function to create a Vec3 object and return its string representation.
  assert create_vec3_str(1, 2, 3) == "(1, 2, 3)"
  assert create_vec3_str(4, 5, 6) == "(4, 5, 6)"
  assert create_vec3_str(7, 8, 9) == "(7, 8, 9)"
output: def create_vec3_str(x, y, z):
      return f"({x}, {y}, {z})"