code: def test_activation(self):
      instance = MusculotendonDeGroote2016(
          self.name,
          self.pathway,
          self.activation,
      )
      assert hasattr(instance, "a")
      assert hasattr(instance, "activation")
      a_expected = dynamicsymbols("a_name")
      assert instance.a == a_expected
      assert instance.activation == a_expected
  
imports: import abc
  import pytest
  from sympy.core.expr import UnevaluatedExpr
  from sympy.core.numbers import Float, Integer, Rational
  from sympy.core.symbol import Symbol
  from sympy.functions.elementary.exponential import exp
  from sympy.functions.elementary.hyperbolic import tanh
  from sympy.functions.elementary.miscellaneous import sqrt
  from sympy.functions.elementary.trigonometric import sin
  from sympy.matrices.dense import MutableDenseMatrix, eye, zeros
  from sympy.physics.biomechanics.activation import FirstOrderActivationDeGroote2016
  from sympy.physics.biomechanics.curve import CharacteristicCurveCollection, FiberForceLengthActiveDeGroote2016, FiberForceLengthPassiveDeGroote2016, FiberForceLengthPassiveInverseDeGroote2016, FiberForceVelocityDeGroote2016, FiberForceVelocityInverseDeGroote2016, TendonForceLengthDeGroote2016, TendonForceLengthInverseDeGroote2016
  from sympy.physics.biomechanics.musculotendon import MusculotendonBase, MusculotendonDeGroote2016, MusculotendonFormulation
  from sympy.physics.biomechanics._mixin import _NamedMixin
  from sympy.physics.mechanics.actuator import ForceActuator
  from sympy.physics.mechanics.pathway import LinearPathway
  from sympy.physics.vector.frame import ReferenceFrame
  from sympy.physics.vector.functions import dynamicsymbols
  from sympy.physics.vector.point import Point
  from sympy.simplify.simplify import simplify
label_desc: Use image node_id 13 for calling the TestMusculotendonDeGroote2016 obj's underlying member method code with example usage: obj.test_activation() without return types