Can I make an individual Dynamic parameter time-dependent?

In Dynamic parameter values — param v1.12.3, we’re shown how to turn time dependence on for all Dynamic parameters. Is there any way to control this on the per-parameter or per-instance level, for example to make one particular parameter time-dependent?

import param

class Foo(param.Parameterized):
    a = param.Dynamic()
    b = param.Dynamic()

foo = Foo()
foo.param.a.time_dependent
# False
foo.param.b.time_dependent
# False

# foo.param.a.time_dependent = True
# AttributeError: 'Dynamic' object attribute 'time_dependent' is read-only

param.Dynamic.time_dependent = True
foo.param.a.time_dependent
# True
foo.param.b.time_dependent
# True