Instantiating Elliptic Curve Isogenies using rational maps

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I have an elliptic curve $$E: y^2 = x^3+x$$ and the rational maps for a degree 14 isogeny $\phi =(\phi_x,\phi_y)$. I would like to get an Isogeny object using $\phi_x,\phi_y$ so I can use some of the functionality of the Isogeny class, but I can't seem to find anything in the sagemath documentation about this.

Currently sage allows you to construct either cyclic isogenies by specifying a point $P$ on $E$; or by the kernel polynomial provided the degree is either odd or the polynomial is divisible by $x^3+x$.

EDIT: I've looked the the code of the EllipticCurveIsogeny class and the attributes for the x and y rational maps are private attributes. I cannot figure out a way to create an Isogeny object with my desired rational maps.