I am writing a code or a calculation of a very complicated function and my main variable is $x$ such that $-1<x<1$. This assumption has to simplify my final answer a lot, but since the final answer is very complicated (20-30 lines!), the FullSimplify condition does not return anything back and if I use the assumption at the end of the calculation, it again does not give anything back (it runs forever).
So, I have broken the calculation down to small bits, where in every small part I calculate a function of $x$. But, I do not want to re-evaluate the result of each function by re-writing the assumption $Abs[x]<1$. Is there a way to define $x$ at the start of the code such that whenever there is an $x$ is the code, Mathematica will take it to be such that $Abs[x]<1$? I.e., can I define $x$ with this condition globally?