Rewriting a power as an exponential: pow2exp

Powers with arbitrary (positive) bases are often defined in terms of exponentials with base e with

a^x = e^x ln(a)

The pow2exp rewrites powers to exponentials.

pow2exp takes one argument:
expr, an exponential.
pow2exp(expr) returns expr with any powers replaced by their corresponding exponential.

Example.
Input:

pow2exp(a^(x+y))

Output:

⎛
⎝

x+y

⎞
⎠

lna