When field size is of the form $p^m$, where $p$ is a prime and $m>1$ is a positive integer there is no problem. For example
F.<x> = GF(5^2)
print F.fetch_int(4)
It outputs : 4.
But if we take field size is in the form $p^1$, then the above code does not working. For example
F.<x> = GF(5^1)
print F.fetch_int(4)
It gives errors. How can I fix this ?