Indefinite Integrals for Function objects

[giovaniceotto]

Is your feature request related to a problem? Please describe.

No.

Describe the solution you'd like

Indefinite Integrals for Function objects

[Gui-FernandesBR]

Please describe where/when this could be useful

[Gui-FernandesBR]

Maybe the new Function.integral_function() method already addressed this issue.
Needs confirmation.

[Gui-FernandesBR]

Confirmed by @giovaniceotto that it was solved by enh/liquid-motors development