I learned that the Fourier representation of a periodic function $f(t)$ with period $T$ is $\sum \limits_{k=-\infty}^{\infty} C_k e^{i2\pi k t/T}$ with appropriate constants $\{C_k\}$.
My question: Is it possible to have a similar representation if the period is also a function of $t$, $T_t$?
(I am not a mathematician. So, kindly explain your answer in details, and also cite appropriate books and papers, if possible. Thanks!)