conjugate of scalar field

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I'm new to SageMath.

I was wondering how to form the conjugate of a complex scalar function on a Lorentzian manifold. This is useful for calculating Newman Penrose spin coefficients. According to the SageMath documentation, one can apply standard math functions (eg abs()) but as far as I can see there is no conjugate, real or imaginary part capability for scalar fields. For example trying conjugate(f) leads to:

TypeError: cannot coerce arguments: no canonical
coercion from Algebra of differentiable scalar fields on
the 4-dimensional Lorentzian manifold M to Symbolic Ring

On the other hand using SageManifolds to differentiate abs(f(t)) where f(t) is a scalar function leads to:

dabs(f) = 1/2*(conjugate(d(f)/dt)*f(t) + conjugate(f(t))*d(f)/dt)/abs(f(t)) dt

I'm not sure if this is a misunderstanding on my part or a missing feature.